criyle/codenet-compile-errors huggingface dataset:
Language: C++

#include <iostream>
#include <vector>

using namespace std;
using ll = long long;
using ull = unsigned long long;

int N;
ll K;
vector<ll> P, M, Z;

bool judge_m(ll mid) {
    ll sum = 0;
    for (int i = 0; i < (int)P.size(); i++) {
        ll d = (mid - P[i] + 1) / P[i];
        sum += upper_bound(M.begin(), M.end(), d) - M.begin();
    }
    return sum >= K;
}

bool judge_p(ll mid) {
    ll sum = 0;
    for (int i = 0; i < (int)P.size(); ++i) {
        ll d = mid / P[i];
        ll tmp = upper_bound(P.begin(), P.end(), d) - P.begin();
        if (i < tmp) tmp--;
        sum +=tmp;
    }
    for (int i = 0; i < (int)M.size(); ++i) {
        ll d = mid / M[i];
        ll tmp = upper_bound(M.begin(), M.end(), d) - M.begin();
        if (i < tmp) tmp--;
        sum += tmp;
    }
    sum /= 2;
    return sum >= K;
}

const int MAX = 510000;
const int MOD = 1000000007;

ll fac[MAX], finv[MAX], inv[MAX];

int main() {

    cin >> N >> K;
    vector<ll> A(N); for (auto& x:A) cin >> x;
    for (auto& x:A) {
        if (x > 0) {
            P.push_back(x);
        } else if (x < 0) {
            M.push_back(x);
        } else {
            Z.push_back(x);
        }
    }
    ll p = P.size();
    ll m = M.size();
    ll z = Z.size();

    ll minus = p * m;
    ll zero = z * (z - 1) / 2 + z * p + z * m;
    ll plus = p * p + m * m;
    
    if (K <= minus){
        sort(M.begin(), M.end());
        ll l = -1e18 - 1, u = -1;
        while (u - l > 1) {
            ll mid = (u + l) / 2;
            if (judge_m(mid)) {
                u = mid;
            } else {
                l = mid;
            }
        }
        cout << u << endl;
    }else if (K <= minus + zero) {
        cout << 0 << endl;
    }else {
        K -= (minus + zero);
        for (int i = 0; i < m; ++i) {
            M[i] = abs(M[i]);
        }
        sort(P.begin(), P.end());
        sort(M.begin(), M.end());
        ll l = -1, u = 1e18;
        while (u - l > 1) {
            ll mid = (u + l) / 2;
            if (judge_p(mid)) {
                u = mid;
            } else {
                l = mid;
            }
        }
        cout << u << endl;
    }
    return 0;
}

Compiler output:
a.cc: In function 'bool judge_m(ll)':
a.cc:16:16: error: 'upper_bound' was not declared in this scope
   16 |         sum += upper_bound(M.begin(), M.end(), d) - M.begin();
      |                ^~~~~~~~~~~
a.cc: In function 'bool judge_p(ll)':
a.cc:25:18: error: 'upper_bound' was not declared in this scope
   25 |         ll tmp = upper_bound(P.begin(), P.end(), d) - P.begin();
      |                  ^~~~~~~~~~~
a.cc:31:18: error: 'upper_bound' was not declared in this scope
   31 |         ll tmp = upper_bound(M.begin(), M.end(), d) - M.begin();
      |                  ^~~~~~~~~~~
a.cc: In function 'int main()':
a.cc:66:9: error: 'sort' was not declared in this scope; did you mean 'short'?
   66 |         sort(M.begin(), M.end());
      |         ^~~~
      |         short
a.cc:84:9: error: 'sort' was not declared in this scope; did you mean 'short'?
   84 |         sort(P.begin(), P.end());
      |         ^~~~
      |         short
Language: C++

#include <cstdio>
#include <algorithm>
#define maxn 200010
#define LL long long
using namespace std;
int a[maxn],fu,zero,zh,b[maxn],c[maxn],d[maxn],tot;
struct node{
	int v,flag;//flag==0 负,flag==1 正
}e[maxn];
int sum[2][maxn];
int cmp(node a,node b){
	return a.v<b.v;
}
int myabs(int a){
	return a>=0?a:-a;
}
int main(){
	int n,i,cnt,j;
	LL k;
	scanf("%d%lld",&n,&k);
	for(i=1;i<=n;i++)scanf("%d",&a[i]);
	sort(a+1,a+1+n);
	for(i=1;i<=n;i++)
		if(a[i]<0)b[fu++]=a[i],e[++tot].v=myabs(a[i]),e[tot].flag=0;
		else if(a[i]==0)c[zero++]=a[i];
		else if(a[i]>0)d[zh++]=a[i],e[++tot]=a[i],e[tot].flag=1;
	if(k<=(LL)fu*zh){//乘积为负
		printf("%lld\n",(LL)b[k/zh]*d[k%zh]);
	}else if(k<=(LL)fu*zh+(LL)zero*(fu+zh)+(LL)zero*(zeo-1)/2){//乘积为0
		printf("0\n");
	}else{//乘积为正
		sort(e+1,e+1+tot,cmp)
		for(i=1;i<=tot;i++){
			sum[0][i]=sum[0][i-1],sum[1][i]=sum[1][i-1];
			if(e[i].flag==0)sum[0][i]+=1;
			else if(e[i].flag==1)sum[1][i]+=1;
		}
		k-=(LL)fu*zh+(LL)zero*(fu+zh)+(LL)zero*(zeo-1)/2;
		for(i=1;i<=tot;i++){
			if(e[i].flag==1){
				if(k>sum[1][i-1])k-=sum[1][i-1];
				else{
					for(j=1;j<i;j++)
						if(k==sum[1][j]){
							printf("%lld\n",(LL)e[i].v*e[j].v);
							return 0;
						}
				}				
			}else if(e[i].flag==0){
				if(k>sum[0][i-1])k-=sum[0][i-1];
				else{
					for(j=1;j<i;j++)
						if(k==sum[0][j]){
							printf("%lld\n",(LL)e[i].v*e[j].v);
							return 0;
						}
				}
			}
		}	
	}
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:26:57: error: no match for 'operator=' (operand types are 'node' and 'int')
   26 |                 else if(a[i]>0)d[zh++]=a[i],e[++tot]=a[i],e[tot].flag=1;
      |                                                         ^
a.cc:7:8: note: candidate: 'constexpr node& node::operator=(const node&)'
    7 | struct node{
      |        ^~~~
a.cc:7:8: note:   no known conversion for argument 1 from 'int' to 'const node&'
a.cc:7:8: note: candidate: 'constexpr node& node::operator=(node&&)'
a.cc:7:8: note:   no known conversion for argument 1 from 'int' to 'node&&'
a.cc:29:58: error: 'zeo' was not declared in this scope; did you mean 'zero'?
   29 |         }else if(k<=(LL)fu*zh+(LL)zero*(fu+zh)+(LL)zero*(zeo-1)/2){//乘积为0
      |                                                          ^~~
      |                                                          zero
a.cc:32:38: error: expected ';' before 'for'
   32 |                 sort(e+1,e+1+tot,cmp)
      |                                      ^
      |                                      ;
   33 |                 for(i=1;i<=tot;i++){
      |                 ~~~                   
a.cc:33:35: error: expected ';' before ')' token
   33 |                 for(i=1;i<=tot;i++){
      |                                   ^
      |                                   ;
Language: Java

import java.util.Scanner;
import java.util.Arrays;
public class Main {
    public static void main(String[] args) {
        Scanner sc =new Scanner(System.in);
        long n =sc.nextLong();long k =sc.nextLong();long[] array = new long[n];long[] new_array = new long[n*(n-1)/2];
        for(int i=0;i<n;i++)
            array[i]=sc.nextLong();
        int time=0;
        for(int i=0;i<n;i++){
            for(int j=i+1;j<n;j++){
                new_array[time]=array[i]*array[j];
                time++;
            }
        }
        Arrays.sort(new_array);
        System.out.println(new_array[k-1]);
}
    }

Compiler output:
Main.java:6: error: incompatible types: possible lossy conversion from long to int
        long n =sc.nextLong();long k =sc.nextLong();long[] array = new long[n];long[] new_array = new long[n*(n-1)/2];
                                                                            ^
Main.java:6: error: incompatible types: possible lossy conversion from long to int
        long n =sc.nextLong();long k =sc.nextLong();long[] array = new long[n];long[] new_array = new long[n*(n-1)/2];
                                                                                                                  ^
Main.java:17: error: incompatible types: possible lossy conversion from long to int
        System.out.println(new_array[k-1]);
                                      ^
3 errors
Language: C++

#include <iostream>
#include <vector>

using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < n; ++i)

int main() {
    int n;
    ll k;
    cin >> n >> k;
    ll INF = ll(1e18) + 1;
    vector<ll> a(n);
    rep(i, n) cin >> a[i];
    sort(a.begin(), a.end());
    ll lhs = -INF;
    ll rhs = INF;
    while (rhs - lhs > 1){
        ll x = (lhs + rhs) / 2;
        ll tot = 0;
        rep(i, n) {
            if (a[i] < 0){
                int l = -1, r = n;
                while (r - l > 1){
                    int cent = (l + r) / 2;
                    if (a[i] * a[cent] < x){
                        r = cent;
                    }else{
                        l = cent;
                    }
                }
                tot += (n - r);
            }else {
                int l = -1, r = n;
                while (r - l > 1) {
                    int cent = (l + r) / 2;
                    if (a[i] * a[cent] < x) {
                        l = cent;
                    } else {
                        r = cent;
                    }
                }
                tot += (l + 1);
            }
            if (a[i] * a[i] < x){
                tot--;
            }
        }
        tot /= 2;
        if (tot < k){
            lhs = x;
        }else {
            rhs = x;
        }
    }
    cout << lhs << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:15:5: error: 'sort' was not declared in this scope; did you mean 'short'?
   15 |     sort(a.begin(), a.end());
      |     ^~~~
      |     short
Language: C++

//解説あり、他者回答参考
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <vector>
#include <set>
#include <queue>
#include <map>
#include <string>

#define rep(i, a, b) for ( int i = (a); i < (b); i++ )
#define per(i, a, b) for ( int i = (b)-1; i >= (a); i--)
#define pb push_back
#define mp make_pair
#define bg begin()
#define en end()


using namespace std;

typedef long long ll;

static const long long MOD = 1000000007;
static const long long INF = 20000000000 00000007;

ll N, K;
ll a[200005]; 

// 0 1 2 3 4
// i   l r
int main(void) {
    scanf("%lld %lld", &N, &K);
    rep(i, 0, N) {
        scanf("%lld", &a[i]);
    }
    sort(a, a+N);
    ll l = -INF, r = INF; //自分未満がK個未満の最大値がK番目
    while (r-l>1) {
        ll m = (r + l) / 2;
        ll cnt = 0;
        for (int i=0; i<N; i++) { //全てのa[i]についてm未満となる組み合わせの個数を調べる
            ll s = i, t = N;
            if (a[i]<0) {
                while(t-s>1) {
                    ll u = (s + t) / 2;
                    if (a[i]*a[u]<m) t = u;
                    else s = u;
                }
                cnt += N-t;
            } else {
                while (t-s>1) {
                    ll u = (s + t) / 2;
                    if (a[i]*a[u]<m) s = u;
                    else t = u;
                }
                cnt += s-i;
            }

        }
        if (cnt<K) l = m;
        else r = m;
    }
  
    printf("%lld\n", l);

    return 0;
}



Compiler output:
a.cc:25:42: error: expected ',' or ';' before numeric constant
   25 | static const long long INF = 20000000000 00000007;
      |                                          ^~~~~~~~
Language: C++

//
//
//  d.cpp - created by yugo
//
#include <iostream>
#include <algorithm>
using namespace std;

int main(int argc, char *argv[]){
  int N,K,NN;
  cin >> N >> K;
  NN = N*(N-1)/2;
  int*a = (int*)malloc(sizeof(int) * N);
  long int *b = (int*)malloc(sizeof(long int) * NN);
  for(int i=0; i<N; i++)
    cin >> a[i];

  int l=0;
  for(int i=0; i<N-1; i++)
    for(int j=i+1; j<N; j++)
      b[l++] = a[i] * a[j];

  sort(&b[0],&b[NN-1]);

  cout << b[K-1] << endl;
}


Compiler output:
a.cc: In function 'int main(int, char**)':
a.cc:14:17: error: cannot convert 'int*' to 'long int*' in initialization
   14 |   long int *b = (int*)malloc(sizeof(long int) * NN);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                 |
      |                 int*
Language: C++

#include <algorithm>
#include <cmath>
#include <climits>
#include <cstdlib>
#include <iostream>
#include <numeric>
#include <vector>
typedef long long LL;

std::vector<LL> pos, neg;

LL count(LL v) {
  LL cnt = 0;
  for (LL x : pos) {
    LL y = v / x;
    cnt += std::upper_bound(pos.begin(), pos.end(), y) - pos.begin();
    if (x * x <= v) --cnt;
  }

  for (LL x : neg) {
    LL y = v / x;
    cnt += std::upper_bound(neg.begin(), neg.end(), y) - neg.begin();
    if (x * x <= v) --cnt;
  }

  return cnt/2;
}

int main() {
  LL N, K; std::cin >> N >> K;
  LL zero = 0;
  for (int i = 0; i < N; ++i) {
    LL a; std::cin >> a;
    if (a < 0)       neg.push_back(a);
    else if (a > 0 ) pos.push_back(a);
    else             ++zero;
  }

  std::sort(neg.begin(), neg.end());
  std::sort(pos.begin(), pos.end());

  LL neg_patterns = neg.size() * pos.size();
  if (neg_patterns >= K) {  // answer is neg x pos
    int neg_idx = K / neg.size();
    K -= neg_idx * pos.size();
    LL a = neg[neg_idx];
    LL b = pos[K-1];
    LL ans = a * b;
    std::cout << ans << std::endl;
    return 0;
  }
  K -= neg_patterns;

  LL zero_patterns = zero * (neg.size()+pos.size()) + zero * (zero-1) / 2;
  if (zero_patterns >= K) {
    std::cout << 0 << std::endl;
    return 0;
  }
  K -= zero_patterns;

  assert(false);
  auto tmp = neg;
  for (int i = 0; i < neg.size(); ++i) {
    neg[i] = std::abs(tmp[tmp.size()-i-1]);
  }

  LL ng  = 0;
  LL ok  = 1e18;
  while (ng + 1LL != ok) {
    LL mid = (ok + ng) / 2;
    if (count(mid) >= K) ok = mid;
    else                 ng = mid;
  }
  std::cout << ok << std::endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:61:3: error: 'assert' was not declared in this scope
   61 |   assert(false);
      |   ^~~~~~
a.cc:8:1: note: 'assert' is defined in header '<cassert>'; this is probably fixable by adding '#include <cassert>'
    7 | #include <vector>
  +++ |+#include <cassert>
    8 | typedef long long LL;
Language: C++

#include <iostream>
#include <set>
#include <vector>

using namespace std;

int main() {
    int len;
    cin >> len;
    int k;
    cin >> k;
    vector<long> num_list;
//    multiset<long> ms;
    vector<long> multiples;
    for (int i = 0; i < len; i++){
        int num;
        cin >> num;
        num_list.push_back(num);
    }
    for (int i = 0; i < len - 1; i++){
        for (int a = 0; a < len - i - 1; a++){
            multiples.push_back(num_list[i] * num_list[a + i + 1]);
        }
    }
    sort(multiples.begin(), multiples.end());
    cout << multiples[k] << endl;
//    int cnt = 0;
//    for (auto itr = ms.begin(); itr != ms.end(); ++itr){
//        cnt++;
//        if (cnt == k){
//            cout << *itr << endl;
//            break;
//        }
//    }
}


Compiler output:
a.cc: In function 'int main()':
a.cc:25:5: error: 'sort' was not declared in this scope; did you mean 'short'?
   25 |     sort(multiples.begin(), multiples.end());
      |     ^~~~
      |     short
Language: Java

public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		System.out.println(0);
		}
		}


Compiler output:
Main.java:3: error: cannot find symbol
		Scanner sc=new Scanner(System.in);
		^
  symbol:   class Scanner
  location: class Main
Main.java:3: error: cannot find symbol
		Scanner sc=new Scanner(System.in);
		               ^
  symbol:   class Scanner
  location: class Main
2 errors
Language: C++


import numpy as np


# 解がマイナスのとき
def solve1(k, ml, pl):
    left, right = -(10 ** 18) - 1, 0
    while right - left > 1:
        c = (left + right) // 2
        n = 0
        for x in ml:
            y = np.ceil(c / x)
            n += len(pl) - np.searchsorted(pl, y)
        if k <= n:
            right = c
        else:
            left = c
    return right


# 解がプラスのとき
def solve2(k, ml, pl):
    left, right = 0, 10 ** 18
    while right - left > 1:
        c = (left + right) // 2
        n = 0
        for x in ml:
            y = c // x
            n += len(ml) - np.searchsorted(ml, y)
            if y <= x:
                n -= 1
        for x in pl:
            y = c // x
            n += np.searchsorted(pl, y, side="right")
            if x <= y:
                n -= 1
        n /= 2
        if k <= n:
            right = c
        else:
            left = c
    return right
        

def main():
    N, K = list(map(int, input().split()))
    A = np.array(input().split(), dtype=int)
    A.sort()
    ml = A[A < 0]
    pl = A[A > 0]
    zl = A[A == 0]
    mn = len(ml) * len(pl)
    zn = sum([N - i for i in range(1, len(zl) + 1)])
    if K <= mn:
        ans = solve1(K, ml, pl)
    elif K <= mn + zn:
        ans = 0
    else:
        ans = solve2(K - mn - zn, ml, pl)
    print(ans)


if __name__ == "__main__":
    main()


Compiler output:
a.cc:5:3: error: invalid preprocessing directive #\U000089e3\U0000304c\U000030de\U000030a4\U000030ca\U000030b9\U0000306e\U00003068\U0000304d
    5 | # 解がマイナスのとき
      |   ^~~~~~~~~~~~~~~~~~
a.cc:21:3: error: invalid preprocessing directive #\U000089e3\U0000304c\U000030d7\U000030e9\U000030b9\U0000306e\U00003068\U0000304d
   21 | # 解がプラスのとき
      |   ^~~~~~~~~~~~~~~~
a.cc:2:1: error: 'import' does not name a type
    2 | import numpy as np
      | ^~~~~~
a.cc:2:1: note: C++20 'import' only available with '-fmodules-ts'
Language: C++

#include <bits/stdc++.h>
using namespace std;

int main() {
  int N,K;
  cin >> N >> K;
  vector<int64_t> A(N);
  vector<int64_t> M(0);
  
  for(int i = 0; i < N; i++){
  	cin >> A.at(i);
  }
  
  sort(A.at(i),A.at(j));
  
  for(int i = 0; i < N; i++){
  	for(int j = i+1; j < N; j++){
    	M.push_back(A.at(i)*A.at(j));
    }
  }

  sort(M.begin(),M.end());
  
  cout << M.at(K-1) << endl;

}


Compiler output:
a.cc: In function 'int main()':
a.cc:14:13: error: 'i' was not declared in this scope
   14 |   sort(A.at(i),A.at(j));
      |             ^
a.cc:14:21: error: 'j' was not declared in this scope
   14 |   sort(A.at(i),A.at(j));
      |                     ^
Language: C++

30 413
-170202098 -268409015 537203564 983211703 21608710 -443999067 -937727165 -97596546 -372334013 398994917 -972141167 798607104 -949068442 -959948616 37909651 0 886627544 -20098238 0 -948955241 0 -214720580 277222296 -18897162 834475626 0 -425610555 110117526 663621752 0

Compiler output:
a.cc:1:1: error: expected unqualified-id before numeric constant
    1 | 30 413
      | ^~
Language: C++

#include <cstdio>
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main(){
    int n,k;
    vector<long long int> v;
    scanf("%d %d",&n,&k);
    long long int a;
    a = new long long int[n];
    for(int i=0;i<n;i++){
        scanf("%lld",&a[i]);
    }    
 
    for(int i=0;i<n-1;i++){
        for(int j=i+1;j<n;j++){
            v.push_back(a[i]*a[j]);
        }
    }
    sort(v.begin(),v.end());
    cout << v[k-1] << endl;
    delete[] a;
    return 0;
 
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:9: error: invalid conversion from 'long long int*' to 'long long int' [-fpermissive]
   11 |     a = new long long int[n];
      |         ^~~~~~~~~~~~~~~~~~~~
      |         |
      |         long long int*
a.cc:13:24: error: invalid types 'long long int[int]' for array subscript
   13 |         scanf("%lld",&a[i]);
      |                        ^
a.cc:18:26: error: invalid types 'long long int[int]' for array subscript
   18 |             v.push_back(a[i]*a[j]);
      |                          ^
a.cc:18:31: error: invalid types 'long long int[int]' for array subscript
   18 |             v.push_back(a[i]*a[j]);
      |                               ^
a.cc:23:14: error: type 'long long int' argument given to 'delete', expected pointer
   23 |     delete[] a;
      |              ^
Language: C++

#include <cstdio>
#include <algorithm>
#include <queue>
#define maxn 200005
using namespace std;

typedef long long LL;

LL a[maxn];
int n, k;

int main(int argc, char** argv)
{
	scanf("%d%d", &n, &k);
	LL *products = new LL[k];
	for(int i=0; i<n; i++)
		scanf("%I64d", a + i);
	int cnt = 0;
	for(int i=0; i<n; i++)
		for(int j=i+1; j<n; j++)
		{
			if(cnt < k) 
			{
				products[cnt] = a[i] * a[j];
			}
			else
			{
				if (cnt == k)
					sort(products, products + cnt);
				value = a[i] * a[j];
				if(value < products[k-1])
				{
					if(k == 1)
						products[k-1] = value;
					else
					{
						int pos = k - 2;						
						while(pos >=0 && products[pos] > value)
						{
							products[pos+1] = products[pos];
						}
						products[pos] = value;
					}
				}				
			}
			cnt++;
		}
	printf("%I64d\n", products[k-1]);
	delete[] products;
	return 0;
}

Compiler output:
a.cc: In function 'int main(int, char**)':
a.cc:30:33: error: 'value' was not declared in this scope
   30 |                                 value = a[i] * a[j];
      |                                 ^~~~~
Language: C++

#include <cstdio>
#include <algorithm>
#define maxn 200005
using namespace std;

typedef long long LL;

int n, rpos, a[maxn];
LL k;

inline LL C(const LL& n) { return n * (n - 1) >> 1; }

inline LL floordiv(LL a, LL b)
{
    bool f = (a < 0) ^ (b < 0); // '^' is '!='
    if(a < 0) a = -a;
    if(b < 0) b = -b;
    return f? -(a / b + 1): a / b;
}

inline LL ceildiv(LL a, LL b)
{
    bool f = (a < 0) ^ (b < 0);
    if(a < 0) a = -a;
    if(b < 0) b = -b;
    return f? -(a / b): (a - 1) / b + 1; // (a - 1) / b + 1 = ceil(a * 1.0 / b)
}

int main()
{
	scanf("%d%lld", &n, &k);
	for(int i=1; i<=n; i++) scanf("%d", a + i);
	sort(a + 1, a + n + 1);
	LL l = 0, r = 0, z = 0, L = 0, R = 0, Z = 0; // l: negativecnt, r: positivecnt, z: zerocnt
	for(int i=1; i<=n; i++)
		z += a[i] == 0,
		l += a[i] < 0,
		r += a[i] > 0;
	// L: cnt of res < 0, R: cnt of res > 0, Z: cnt of res == 0
    L = l * r; R = C(l) + C(r); Z = C(n) - L - R;
    rpos = n + 1; // rpos: the first positive number in a
    for(int i=1; i<=n; i++)
		if(a[i] > 0)
		{
	        rpos = i;
			break;
    	}
	if(k <= L) // answer is negative
	{
		LL ql = -1e18, qr = -1, mid, ans = -233;
		while(ql <= qr)
		{
			mid = ql + qr >> 1;
			LL sum = 0, now = r, cur = rpos;
			for(int i=1; i<=n && a[i]<0; i++)
			{
				LL up = (mid % a[i] == 0)? (mid / a[i] + 1): ceildiv(mid, a[i]); // NOTE: mid / a[i] + 1 ok?
				while(now && a[cur] < up) cur ++, now --;
				sum += now;
			}
			if(sum < k) ql = (ans = mid) + 1;
			else qr = mid - 1;
		}
		printf("%lld\n", ans);
	}
	else if(k <= L + Z) // answer is 0
        puts("0");
    else // answer is positive
	{
        k -= L + Z;
        LL ql = 1, qr = 1e18, mid, ans = -233;
        while(ql <= qr) {
            mid = (ql + qr) >> 1;
            LL sum = 0, now = r, cur = n;
            for(int i = rpos; i <= n; i ++) {
                LL up = mid % a[i] == 0 ? mid / a[i] - 1 : fl(mid, a[i]);
                while(now && a[cur] > up) cur --, now --;
                sum += cur >= i ? now - 1 : now;
            }
            now = l; cur = 1;
            for(int i = n; i >= 1; i --) if(a[i] < 0) {
                LL up = mid / a[i] + 1;
                while(now && a[cur] < up) cur ++, now --;
                sum += cur <= i ? now - 1 : now;
            }
            sum >>= 1;
            if(sum < k) ql = (ans = mid) + 1;
            else qr = mid - 1;
        }
        printf("%lld\n", ans);
    }
    return 0;
} 

Compiler output:
a.cc: In function 'int main()':
a.cc:76:60: error: 'fl' was not declared in this scope; did you mean 'ql'?
   76 |                 LL up = mid % a[i] == 0 ? mid / a[i] - 1 : fl(mid, a[i]);
      |                                                            ^~
      |                                                            ql
Language: C++

#include <bits/stdc++.h>
#define int long long
using namespace std;

vector<int> A;
int N,K;
const int inf=ll(1e18)+1;

signed main(){
	cin>>N>>K;
	A.assign(N,0);
	for(int i=0;i<N;i++)cin>>A[i];
	sort(A.begin(),A.end());
	int l=-inf,r=inf;
	while(l+1<r){
		int x=(l+r)/2;
		int sum=0;
		for(int i=0;i<N;i++){
			if(A[i]>=0){
				int left=-1,right=N;
				while(left+1<right){
					int c=(left+right)/2;
					if(A[c]*A[i]<x)left=c;
					else right=c;
				}
				sum+=right;
			}else{
				int left=-1,right=N;
				while(left+1<right){
					int c=(left+right)/2;
					if(A[c]*A[i]<x)right=c;
					else left=c;
				}
				sum+=N-right;
			}
			if(A[i]*A[i]<x)sum--;
		}
		sum/=2;
		if(sum<K)l=x;
		else r=x;
	}
	cout<<l<<endl;
	return 0;
}


Compiler output:
a.cc:7:15: error: 'll' was not declared in this scope
    7 | const int inf=ll(1e18)+1;
      |               ^~
Language: C

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#define MAX_N 200000 // 2*(10^5)

int asc(const void *a, const void *b) {
  const long *ac = (long *)a;
  const long *bc = (long *)b;
  if (*ac > *bc) return (1);
  if (*ac < *bc) return (-1);
  return (0);
}

int main(void) {
  int N; // 2 <= N <= 2*(10^5)
  long K; // 1 <= K <= (N*(N-1))/2
  long A[MAX_N]; // -10^9 <= Ai <= 10^9

  long MAX_K;
  long *B; // results
  long A_shift;

  int i;
  int j;
  long m;

  scanf("%d %lu", &N, &K);
  rep(i,N) {
    scanf("%ld", &A[i]);
  }
  MAX_K = (N * (N - 1)) / 2;
  (void)MAX_K;
  B = (long *)calloc(MAX_K, sizeof(long));
  if (!B) exit(EXIT_FAILURE);

  m = 0;
  for (i = 0; i < N; i++) {
    A_shift = A[i];
    for (j = i + 1; j < N; j++) {
      B[m] = A_shift * A[j];
      m++;
    }
  }

  qsort(B, MAX_K, sizeof(B[0]), asc);

  // for (m = 0; m < MAX_K; m++) {
  //   printf("%ld\n", B[m]);
  // }

  for (m = 0; m < MAX_K; m++) {
    if (m == (K - 1)) {
      printf("%ld\n", B[m]);
    }
  }

  free(B);
  return (0);
}


Compiler output:
main.c: In function 'main':
main.c:29:3: error: implicit declaration of function 'rep' [-Wimplicit-function-declaration]
   29 |   rep(i,N) {
      |   ^~~
main.c:29:11: error: expected ';' before '{' token
   29 |   rep(i,N) {
      |           ^~
      |           ;
Language: C++

klsdfj;lfds

Compiler output:
a.cc:1:1: error: 'klsdfj' does not name a type
    1 | klsdfj;lfds
      | ^~~~~~
a.cc:1:8: error: 'lfds' does not name a type
    1 | klsdfj;lfds
      |        ^~~~
Language: C++

#include <bits/stdc++.h>
#define rep(i, n) for(int i = 0;i < (n);i++)
using namespace std;
using ll = long long;

const ll INF = ll(1e18) + 1;

int main(){
	int N, K;
  	cin >> N >> K;
	vector<ll> A(N);
  	rep(i, N) cin >> A[i];
  	
  	sort(A.begin(), A.end());
  	
  	ll l = -INF, r = INF;
  	while(l + 1 < r){
    	ll x = (l + r) / 2;
      	bool ok = [&]{
        	ll tot = 0;
          	rep(i, N){
          		if(a[i] < 0){
                	int l = -1, r = n;
                  	while(l + 1 < r){
                    	int c = (l + r) / 2;
                      if(a[c] * a[i] < x) r = c; else l = c;
                    }
                  	tot += n - r;
                } else {
                	int l = -1, r = n;
                  	while(l + 1 < r){
                    	int c = (l + r) / 2;
                      	if(a[c] * a[i] < x) l = c; else r = c;
                    }
                  tot += r;
                }
              
              	if(a[i] * a[i] < x) tot--;
          	}
          	tot /= 2;
          return tot < k;
        }();
      
      	if(ok) l = k; else r = x;
    }
  
  	cout << l << endl;
}

Compiler output:
a.cc: In lambda function:
a.cc:22:28: error: 'a' was not declared in this scope
   22 |                         if(a[i] < 0){
      |                            ^
a.cc:23:41: error: 'n' was not declared in this scope
   23 |                         int l = -1, r = n;
      |                                         ^
a.cc:30:41: error: 'n' was not declared in this scope
   30 |                         int l = -1, r = n;
      |                                         ^
a.cc:38:20: error: 'a' was not declared in this scope
   38 |                 if(a[i] * a[i] < x) tot--;
      |                    ^
a.cc:41:24: error: 'k' was not declared in this scope
   41 |           return tot < k;
      |                        ^
a.cc: In function 'int main()':
a.cc:44:20: error: 'k' was not declared in this scope
   44 |         if(ok) l = k; else r = x;
      |                    ^
Language: C++

//g++ -std=c++14 test.cpp -o test.out
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <cassert>
#include <algorithm>
#include <functional>
#include <iostream>
#include <iomanip>
#include <vector>
#include <queue>
#include <map> 
#include <utility>
#include <limits.h>
using namespace std;
 
#define LL unsigned long long int
const LL INF = LL(1e18)+1
 
LL N,K;
LL A[200000];
 
LL ans;
 
void solve(){
	sort(A,A+N);//とりあえず昇順にソート
	//二部探索開始
	LL left = -INF;//leftはギリギリOKなやつ
	LL right = INF;//rightはギリギリダメなやつ
	while(left+1<right){
		LL x = (left+right)/2;//xがOKなやつかどうかを判定する

		//ラムダ式(関数の簡易バージョンみたいなやつ)でxがOKなやつかどうかを判定
		//&で直前に出てきた、ラムダ式の外の変数を参照できるようになる
		bool ok = [&]{
			//このラムダ式は
			//あるA[i]に対し、
			//A[i]*A[0]、A[i]*A[1]、A[i]*A[2]、......、A[i]A[N-1]
			//のうちx未満の数がいくつあるかを二部探索で求める
			//これをi=0~N-1まで繰り返し
			//totalにその合計を格納
			//totalがkより小さければtrueを返す
			//という機能を持つ
			LL total = 0;//x未満の数がいくつあるかを格納
			for(int i=0;i<N;i++){//Aを順に一個ずつ見ていく
				if(A[i]>=0){//選んだA[i]が正なら
					int l = -1;//条件を満たす数が一個もなければ-1、全部条件を満たすならN-1になる
					int r = N;
					//二部探索
					while(l+1<r){
						int c = (l+r)/2;
						if(A[c]*A[i]<x) l = c;
						else r = c;
					}
					total += r;//結局、考えられるペアはr通り
				}else{//選んだA[i]が負なら
					int l = -1;//条件を満たす数が一個もなければ-1、全部条件を満たすならN-1になる
					int r = N;
					//二部探索
					while(l+1<r){
						int c = (l+r)/2;
						if(A[c]*A[i]<x) r = c;
						else l = c;
					}
					total += (N-r);//結局、考えられるペアはn-r通り
				}
				if(A[i]*A[i]<x) total--;
			}
			total/=2;
			return total<k;
		}();

		if(ok) left = x;
		else right = x;
	}
	ans = left;
}
 
int main(){
	cin >> N >> K;
	for(int i=0;i<N;i++) cin >> A[i];
 
	solve();

	cout << ans << endl;
	return 0;
}

Compiler output:
a.cc:17:12: error: expected primary-expression before 'unsigned'
   17 | #define LL unsigned long long int
      |            ^~~~~~~~
a.cc:18:16: note: in expansion of macro 'LL'
   18 | const LL INF = LL(1e18)+1
      |                ^~
a.cc: In function 'void solve()':
a.cc:26:18: error: 'N' was not declared in this scope
   26 |         sort(A,A+N);//とりあえず昇順にソート
      |                  ^
a.cc: In lambda function:
a.cc:70:38: error: 'k' was not declared in this scope; did you mean 'ok'?
   70 |                         return total<k;
      |                                      ^
      |                                      ok
a.cc: In function 'int main()':
a.cc:80:16: error: 'N' was not declared in this scope
   80 |         cin >> N >> K;
      |                ^
a.cc:80:21: error: 'K' was not declared in this scope
   80 |         cin >> N >> K;
      |                     ^
Language: Java

import java.util.*;
import java.io.PrintWriter;
public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		long k=sc.nextLong();
		Double[] a=new Double[n];
		long zero=0;
		long plus=0;
		long ma=0;
		ArrayList<Double> p=new ArrayList<>();
		ArrayList<Double> mai=new ArrayList<>();
		for(int i=0; i<n; i++){
			a[i]=sc.nextDouble();
			if(a[i]>0){
				plus++;
				p.add(a[i]);
			}else if(a[i]<0){
				ma++;
				mai.add(a[i]);
			}else{
				zero++;
			}
		}
		long l=-1000000000000000000L;
		long r=1000000000000000001L;
		if(ma*plus>=k){
			r=0;
		}else if(ma*plus+zero*((n-1)*n/2-(zero-1)*zero/2)>=k){
			System.out.println(0);
			return;
		}else{
			l=1;
		}
		Collections.sort(p,reverseOrder());
		Collections.sort(mai);
		while(r-l>1){
			long m=(r+l)/2;
			long count=0;
			for(int i=0; i<n; i++){
				int in=0;
				if(m>0){
					if(a[i]<0){
						in=-Collections.binarySearch(mai,m/a[i]+0.1)-1;
					}else{
						in=-Collections.binarySearch(p,m/a[i]+0.1)-1;
					}
				}else{
					if(a[i]<0){
						in=-Collections.binarySearch(p,m/a[i]-0.1)-1;
					}else{
						in=-Collections.binarySearch(mai,m/a[i]+0.1)-1;
					}
				}
				count+=in;
			}
			System.out.println(count+" "+m);
			if(count/2<k){
				l=m;
			}else{
				r=m;
			}
		}
		System.out.println(l+1);
	}
}


Compiler output:
Main.java:36: error: cannot find symbol
		Collections.sort(p,reverseOrder());
		                   ^
  symbol:   method reverseOrder()
  location: class Main
1 error
Language: C++

#include <bits/stdc++.h>
using namespace std;

using ll = long long;


ll N,K;

int my_b_search(ll key,ll val,bool mode,vector<int64_t>& A){
    //mode -> true ならば昇順での二分探索 falseなら降順での二分探索
    int ok = mode ? -1 : N;
    int ng = mode ? N : -1;
    while(abs(ok-ng)>1){
        int mid=(ok+ng)/2;
        if(val*A[mid]<=key)ok=mid;
        else ng=mid;
    }
    return ok;
}

bool f(ll key,vector<int64_t>& A){
    ll cnt=0;
    for(int i=0;i<N;i++){
        if(A[i]>=0){
            cnt+=my_b_search(key,A[i],true,A)+1;
        }else{
            cnt+=N-my_b_search(key,A[i],false,A);
        }
        if(key>=A[i]*A[i])cnt--;
    }
    return cnt>=2*K;
}


int main(){
    
    cin>>N>>K;
    vector<int64_t> A(N);

    for(int64_t& a:A){
        cin>>a;
    }

    sort(A.begin(),A.end());

    int64_t ok=1e18,ng=-1e18;
    rep(i,70){
        int64_t mid=(ok+ng)/2;

        if(f(mid,A)){
            ok=mid;
        }else{
            ng=mid;
        }
    }

    cout<<ok<<endl;

}

Compiler output:
a.cc: In function 'int main()':
a.cc:47:9: error: 'i' was not declared in this scope
   47 |     rep(i,70){
      |         ^
a.cc:47:5: error: 'rep' was not declared in this scope
   47 |     rep(i,70){
      |     ^~~
Language: C++

#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
using namespace std;
const int N = 2e5 + 2;
long long a[N];
int n,m,t;
bool solve(long long ans)
{
	long long cnt = 0;
	for (int i = 1; i <= n; i++)
	{
		
		if (a[i] == 0) {
			if (ans > 0) 
				cnt += n;
		}		
		else if (a[i] > 0)
		{
			long long h = ans / a[i];
			if (ans >= 0) {
				if (ans % a[i])
					h++;
				cnt += (long long)(lower_bound(a + 1, a + 1 + n, h) - (a + 1));
			}
			else {
				h--;
				cnt+= (long long)( lower_bound(a + 1, a + 1 + n, h) - (a + 1));
			}
		}
		else
		{
			long long h = ans / a[i];
			if (ans >= 0) {
				if (ans % a[i])
					h--;
				cnt += n - long long(upper_bound(a + 1, a + 1 + n, h) - a - 1);
			}
			else
			{
				if (ans % a[i])
					h++;
				cnt+= cnt += n - long long(upper_bound(a + 1, a + 1 + n, h) - a - 1);
			}


		}


	}
	for (int i = 1; i <= n; i++)
		if (a[i] * a[i] <= ans) cnt--;
	return cnt/2>=m;
}
int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	while (cin>>n>>m)
	{
		for (int i = 1; i <= n; i++)
			cin >> a[i];
		sort(a + 1, a + 1 + n);
		t = upper_bound(a + 1, a + n + 1, 0)-a;
		long long r = max(a[n] * a[n], a[1] * a[1]),l=-r;
		long long mid = l + r >> 1;
		while (l <r)
		{
			if (solve(mid))
				r = mid-1;
			else
				l = mid+1;
			mid = l + r >> 1;
		}
		cout << r << endl;
	}
	return 0;
}

Compiler output:
a.cc: In function 'bool solve(long long int)':
a.cc:38:44: error: expected primary-expression before 'long'
   38 |                                 cnt += n - long long(upper_bound(a + 1, a + 1 + n, h) - a - 1);
      |                                            ^~~~
a.cc:44:50: error: expected primary-expression before 'long'
   44 |                                 cnt+= cnt += n - long long(upper_bound(a + 1, a + 1 + n, h) - a - 1);
      |                                                  ^~~~
Language: C++

#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
using namespace std;
const int N = 2e5 + 2;
long long a[N];
int n,m,t;
bool solve(long long ans)
{
	long long cnt = 0;
	for (int i = 1; i <= n; i++)
	{
		
		if (a[i] == 0) {
			if (ans > 0) 
				cnt += n;
		}		
		else if (a[i] > 0)
		{
			long long h = ans / a[i];
			if (ans >= 0) {
				if (ans % a[i])
					h++;
				cnt += (long long)(lower_bound(a + 1, a + 1 + n, h) - (a + 1));
			}
			else {
				h--;
				cnt+= (long long)( lower_bound(a + 1, a + 1 + n, h) - (a + 1));
			}
		}
		else
		{
			long long h = ans / a[i];
			if (ans >= 0) {
				if (ans % a[i])
					h--;
				cnt += n - long long(upper_bound(a + 1, a + 1 + n, h) - a - 1);
			}
			else
			{
				if (ans % a[i])
					h++;
				cnt+= cnt += n - long long(upper_bound(a + 1, a + 1 + n, h) - a - 1);
			}


		}


	}
	for (int i = 1; i <= n; i++)
		if (a[i] * a[i] <= ans) cnt--;
	return cnt/2>=m;
}
int main()
{
	
	ios_base::sync_with_stdio(false);
	while (cin>>n>>m)
	{
		for (int i = 1; i <= n; i++)
			cin >> a[i];
		sort(a + 1, a + 1 + n);
		t = upper_bound(a + 1, a + n + 1, 0)-a;
		long long r = max(a[n] * a[n], a[1] * a[1]),l=-r;
		long long mid = l + r >> 1;
		while (l <r)
		{
			if (solve(mid))
				r = mid-1;
			else
				l = mid+1;
			mid = l + r >> 1;
		}
		cout << r << endl;
	}
	return 0;

}

Compiler output:
a.cc: In function 'bool solve(long long int)':
a.cc:38:44: error: expected primary-expression before 'long'
   38 |                                 cnt += n - long long(upper_bound(a + 1, a + 1 + n, h) - a - 1);
      |                                            ^~~~
a.cc:44:50: error: expected primary-expression before 'long'
   44 |                                 cnt+= cnt += n - long long(upper_bound(a + 1, a + 1 + n, h) - a - 1);
      |                                                  ^~~~
Language: C++

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 2e5 + 87;
ll n, k, a[N];
ll c0, cn, cp;

ll solvene() {
  vector<ll> neg(a, a + cn);
  vector<ll> pos(a + n - cp, a + n);
  ll lo = neg[0] * pos.back();
  ll hi = neg.back() * pos[0];
  reverse(pos.begin(), pos.end());
  reverse(neg.begin(), neg.end()); // why rev negatives???
  while (lo <= hi) {
    ll mi = lo + (hi - lo) / 2;
    ll cnt = 0;
    // two pointers, count all pairs between neg and pos
    // that are <= the candidate product mi
    // neg:     -5 -4 -3 -2 -1
    // rev neg: -1 -2 -3 -4 -5
    // rev pos:  5  4  3  2  1
    for (ll i = 0, j = 0; i < neg.size(); ++i) {
      for (; j < pos.size() && neg[i] * pos[j] <= mi; ++j); // notice the ; here
      cnt += j;
    }
    if (cnt < k)
      lo = mi + 1;
    else
      hi = mi - 1;
}
  return lo;
}

ll solvenp(ll k) {
  vector<ll> neg(a, a + cn);
  reverse(neg.begin(), neg.end());
  vector<ll> pos(a + n - cp, a + n);
  ll lo = LLONG_MAX;
  ll hi = LLONG_MIN;
  if (neg.size() >= 2) {
    lo = min(lo, neg[0] * neg[1]);
    hi = max(hi, neg[cn - 1] * neg[cn - 2]);
  }
  if (pos.size() >= 2) {
    lo = min(lo, pos[0] * pos[1]);
    hi = max(hi, pos[cp - 1] * pos[cp - 2]);
  }
  while (lo <= hi) {
    ll mi = lo + (hi - lo) / 2;
    ll c = 0;
    // two pointers again, but for (neg * neg) and (pos * pos)
    ll j;
    for (int ll i = 0; i < pos.size(); i++) {
      for (j = i + 1; j < pos.size() && pos[i] * pos[j] <= mi; j++);
      c += j;
    }

    for (ll i = cn - 1, j = 0; i >= 0; --i) {
      for (; j < i && neg[i] * neg[j] <= mi; ++j);
      c += min(j, i);
    }
    if (c < k)
      lo = mi + 1;
    else
      hi = mi - 1;
  }
  return lo;
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> k;
    for (int i = 0; i < n; ++i) {
        cin >> a[i];
        if (a[i] == 0)
            ++c0;
        else if (a[i] > 0)
            ++cp;
        else
            ++cn;
    }

    sort(a, a + n);
    ll ne = cn * cp;
    ll n0 = c0 * (c0 - 1) / 2 + c0 * (n - c0);
    ll np = cp * (cp - 1) / 2 + cn * (cn - 1) / 2;
    ll ans;
    if (k <= ne) {
        ans = solvene();
    } else if (k <= ne + n0) {
        ans = 0;
    } else {
        ans = solvenp(k - ne - n0);
    }
    cout << ans << "\n";
}

Compiler output:
a.cc: In function 'll solvenp(ll)':
a.cc:54:16: error: expected ';' before 'i'
   54 |     for (int ll i = 0; i < pos.size(); i++) {
      |                ^~
      |                ;
a.cc:54:17: error: 'i' was not declared in this scope
   54 |     for (int ll i = 0; i < pos.size(); i++) {
      |                 ^
a.cc:54:38: error: expected ')' before ';' token
   54 |     for (int ll i = 0; i < pos.size(); i++) {
      |         ~                            ^
      |                                      )
a.cc:54:40: error: 'i' was not declared in this scope
   54 |     for (int ll i = 0; i < pos.size(); i++) {
      |                                        ^
Language: Java

import java.util.*;

public class Main {
  private static int N;
  private static long K;
  private static int[] A;
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    N = sc.nextInt();
    K = sc.nextLong();
    A = new int[N];
    for (int i = 0; i < N; i++) {
      A[i] = Integer.paraeInt(sc.next());
    }
    Arrays.sort(A);
    
    long ok = -1_000_000_000_000_000_005L;
    long ng = 1_000_000_000_000_000_005L;
    while (ok+1 < ng) {
      long m = (ok+ng)/2;
      if (isOk(m)) {
        ok = m;
      } else {
        ng = m;
      }
    }
    System.out.println(ok);
  }
  private static boolean isOk(long x) {
    long count = 0;
    for (int i = 0; i < N; i++) {
      count += calcCount(i, x);
    }
    return count/2 < K;
  }
  private static int calcCount(int idx, long x) {
    int ok;
    int ng;
    if (A[idx] >= 0) {
      long max = (long)A[idx]*A[N-1];
      long min = (long)A[idx]*A[0];
      if (max < x) {
        return N-1;
      }
      if (x <= min) {
        return 0;
      }
      ok = 0;
      ng = N-1;
    } else {
      long max = (long)A[idx]*A[0];
      long min = (long)A[idx]*A[N-1];
      if (max < x) {
        return N-1;
      }
      if (x <= min) {
        return 0;
      }
      ok = N-1;
      ng = 0;
    }
    while ((A[idx] >= 0 && ok+1 < ng)
          || (A[idx] < 0 && ng+1 < ok)) {
      int m = (ok+ng)/2;
      if ((long)A[idx]*A[m] < x) {
        ok = m;
      } else {
        ng = m;
      }
    }
    if (A[idx] >= 0) {
      return idx <= ok ? ok : ok+1;
    } else {
      return idx >= ok ? N-ok-1 : N-ok;
    }
  }
}

Compiler output:
Main.java:13: error: cannot find symbol
      A[i] = Integer.paraeInt(sc.next());
                    ^
  symbol:   method paraeInt(String)
  location: class Integer
1 error
Language: C++

#include<iostream>
#include<cstdint>
#include <queue>
#include<vector>
#include <algorithm>
using namespace std;
main(){
  int64_t N,K,sum = 0;
  cin>>N>>K;
  vector<int64_t>A;
  vector<int64_t>minus,zero,plus;
  A.resize(N);
  for(auto &input:A){
    cin>>input;
  }
  for(auto &input:A){
    if(input<0)minus.emplace_back(input);
    else if(input==0)zero.emplace_back(input);
    else plus.emplace_back(input);
  }
  uint64_t minus_sumc,zero_sumc,plus_sumc;
  for(auto &input:A){
    minus_sumc = minus.size()*plus.size();
    zero_sumc = zero.size()*(minus.size()+plus.size())+zero.size()*(zero.size()-1)/2;
    plus_sumc = plus.size()*(plus.size()-1)/2+minus.size()*(minus.size()-1)/2;
  }
  //cout<<minus_sumc<<" "<<zero_sumc<<" "<<plus_sumc<<endl;
  int64_t x = min((int64_t)1000,(int64_t)minus.size());
  int64_t y = min((int64_t)1000,(int64_t)plus.size());
  /*for(auto &output:A){
	cout<<output<<endl;
  }*/
  int size = std::to_string(K).length();
  if(K<=minus_sumc){
    if(size<=5){
      priority_queue<long,vector<long>,greater<long>>ans;
      sort(begin(minus),end(minus));
      sort(rbegin(plus),rend(plus));
      for(int i=0; i<x; i++){
        for(int j=0; j<y; j++){
          ans.push(minus[i]*plus[j]);
        }
      }
      for(int i=0; i < K-1; i++){
        //cout<<ans.top();
        ans.pop();
      }
      cout<<ans.top()<<endl;
    }
    else{
      priority_queue<long>ans;
      sort(rbegin(minus),rend(minus));
      sort(begin(plus),end(plus));
      for(int i=0; i < x; i++){
        for(int j=0; j < y; j++){
          ans.push(minus[i]*plus[j]);
        }
      }
      for(int i=0; i < minus_sumc-K; i++){
        ans.pop();
      }
      cout<<ans.top()<<endl;
    }
  }
  sum+=minus_sumc;
  if(sum < K && K <= sum+zero_sumc){
    cout << 0 <<endl;
  }
  sum+=zero_sumc;
  if(sum < K && K <=sum+plus_sumc){
    if(size<=5){
      sort(rbegin(minus),rend(minus));
      sort(begin(plus),end(plus));
      priority_queue<long,vector<long>,greater<long>>ans;
      for(int i=0; i<x; i++){
        for(int j=i+1; j<x; j++){
          ans.push(minus[i]*minus[j]);
        }
      }
      for(int i=0; i<y; i++){
        for(int j=i+1; j<y; j++){
          ans.push(plus[i]*plus[j]);
        }
      }
      for(int i=0; i < K - sum -1; i++){
        ans.pop();
      }
      cout<<ans.top()<<endl;
    }
    /*else{
      sort(begin(minus),end(minus));
      sort(rbegin(plus),rend(plus));
      priority_queue<long,vector<long>,greater<long>>ans;
      for(int i=0; i<x; i++){
        for(int j=i+1; j<x; j++){
          ans.push(minus[i]*minus[j]);
        }
      }
      for(int i=0; i<y; i++){
        for(int j=i+1; j<y; j++){
          ans.push(plus[i]*plus[j]);
        }
      }
      for(int64_t i=0; i < N*(N-1)/2 - K; i++){
        ans.pop();
      }
      cout<<ans.top()<<endl;
    }
  }*/
}


Compiler output:
a.cc:7:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
    7 | main(){
      | ^~~~
a.cc: In function 'int main()':
a.cc:110:2: error: expected '}' at end of input
  110 | }
      |  ^
a.cc:7:7: note: to match this '{'
    7 | main(){
      |       ^
Language: C++

#include <iostream>
#include <vector>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using namespace std;
typedef long long ll;
typedef pair<int, int> P;

const int MOD = 1E9 + 9;
const ll INF = ll(1e18) + 1;

int main() {
  int n;
  ll k;
  cin >> n >> k;
  vector<ll> a(n);
  rep(i, n) cin >> a[i];
  sort(a.begin(), a.end());
  ll l = -INF, r = INF;
  while (l + 1 < r) {
    ll x = (l + r) / 2;
    bool ok = [&] {
      ll tot = 0;
      rep(i, n) {
        if (a[i] < 0) {
          int l = -1, r = n;
          while (l + 1 < r) {
            int c = (1 + r) / 2;
            if (a[c] * a[i] < x)
              r = c;
            else
              l = c;
          }
          tot += n - r;
        } else {
          int l = -1, r = n;
          while (l + 1 < r) {
            int c = (l + r) / 2;
            if (a[c] * a[i] < x)
              l = c;
            else
              r = c;
          }
          tot += r;
        }
        if (a[i] * a[i] < x) tot--;
      }
      tot /= 2;
      return tot < k;
    }();
    if (ok)
      l = x;
    else
      r = x;
  }
  cout << l << endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:17:3: error: 'sort' was not declared in this scope; did you mean 'short'?
   17 |   sort(a.begin(), a.end());
      |   ^~~~
      |   short
Language: C++

#include <iostream>
#include <vector>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using namespace std;
typedef long long ll;
typedef pair<int, int> P;

const int MOD = 1E9 + 9;
const ll INF = ll(1e18) + 1;

int main() {
  int n;
  ll k;
  cin >> n >> k;
  vector<ll> a(n);
  rep(i, n) cin >> a[i];
  sort(a.begin(), a.end());
  ll l = -INF, r = INF;
  while (l + 1 < r) {
    ll x = (l + r) / 2;
    bool ok = [&]{
      ll tot = 0;
      rep(i, n) {
        if (a[i] < 0) {
          int l = -1, r = n;
          while (l + 1 < r) {
            int c = (1 + r) / 2;
            if (a[c] * a[i] < x)
              r = c;
            else
              l = c;
          }
          tot += n - r;
        } else {
          int l = -1, r = n;
          while (l + 1 < r) {
            int c = (l + r) / 2;
            if (a[c] * a[i] < x)
              l = c;
            else
              r = c;
          }
          tot += r;
        }
        if (a[i] * a[i] < x) tot--;
      }
      tot /= 2;
      return tot < k;
    }();
    if (ok)
      l = x;
    else
      r = x;
  }
  cout << l << endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:17:3: error: 'sort' was not declared in this scope; did you mean 'short'?
   17 |   sort(a.begin(), a.end());
      |   ^~~~
      |   short
Language: C++

#include <iostream>
#include <vector>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using namespace std;
// using long long = long long;
// using P = pair<int, int>;

const int MOD = 1E9 + 9;
const long long INF = (long long)(1e18) + 1;

int main() {
  int n;
  long long k;
  cin >> n >> k;
  vector<long long> a(n);
  rep(i, n) cin >> a[i];
  sort(a.begin(), a.end());
  long long l = -INF, r = INF;
  while (l + 1 < r) {
    long long x = (l + r) / 2;
    bool ok = [&] {
      long long tot = 0;
      rep(i, n) {
        if (a[i] < 0) {
          int l = -1, r = n;
          while (l + 1 < r) {
            int c = (1 + r) / 2;
            if (a[c] * a[i] < x)
              r = c;
            else
              l = c;
          }
          tot += n - r;
        } else {
          int l = -1, r = n;
          while (l + 1 < r) {
            int c = (l + r) / 2;
            if (a[c] * a[i] < x)
              l = c;
            else
              r = c;
          }
          tot += r;
        }
        if (a[i] * a[i] < x) tot--;
      }
      tot /= 2;
      return tot < k;
    }();
    if (ok)
      l = x;
    else
      r = x;
  }
  cout << l << endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:17:3: error: 'sort' was not declared in this scope; did you mean 'short'?
   17 |   sort(a.begin(), a.end());
      |   ^~~~
      |   short