Language: C++

#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

// Optimization

//#pragma GCC optimize("O3")
#define endl '\n'

// Shortcut

#define int long long
#define eb emplace_back
#define pb push_back
#define pob pop_back
#define mp make_pair
#define upb upper_bound
#define lwb lower_bound
#define fi first
#define se second
#define For(i, l, r) for (int i = l; i < r; i++)
#define ForE(i, l, r) for (int i = l; i <= r; i++)
#define Ford(i, r, l) for (int i = r; i > l; i--)
#define FordE(i, r, l) for (int i = r; i >= l; i--)
#define Fora(i, a) for (auto i : a)

// I/O & Debug

#define PrintV(a) Fora(iiii, a) cout << iiii << ' '; cout << endl;
#define PrintVl(a) Fora(iiii, a) cout << iiii << endl;
#define PrintA(a, l, r) for (int iiii = l; iiii <= r; iiii++) cout << a[iiii] << ' '; cout << endl;
#define PrintAl(a, l, r) for (int iiii = l; iiii <= r; iiii++) cout << a[iiii] << endl;
#define Ptest(x) return cout << x, 0;
#define gl(s) getline(cin, s);
#define setpre(x) fixed << setprecision(x)
/*
#define debug(args...){ string _sDEB = #args; replace(_sDEB.begin(), _sDEB.end(), ',', ' '); stringstream _ssDEB(_sDEB); istream_iterator<string> _itDEB(_ssDEB); DEB(_itDEB, args); }
void DEB(istream_iterator<string> it) {}
template<typename T, typename... Args>
void DEB(istream_iterator<string> it, T a, Args... args){
    cout << *it << " = " << a << endl;
    DEB(++it, args...);
}
*/

// Functions

//#define isvowel(a) (a == 'a' || a == 'e' || a == 'i' || a == 'o' || a == 'u')
#define bend(a) a.begin(), a.end()
#define rbend(a) a.rbegin(), a.rend()
#define mset(a) memset(a, 0, sizeof(a))
#define mset1(a) memset(a, 1, sizeof(a))
#define msetn1(a) memset(a, -1, sizeof(a))
#define msetinf(a) memset(a, 0x3f, sizeof(a))
#define gcd __gcd
#define __builtin_popcount __builtin_popcountll
//mt19937 rando(chrono::steady_clock::now().time_since_epoch().count());
//int randt(int l, int r){ return (rando() % (r - l + 1) + l); }

// Data Structure

#define pque priority_queue
#define mts multiset
#define y0 _y0_
#define y1 _y1_
#define div divi
typedef long long ll;
typedef long double ld;
typedef vector <int> vi;
typedef vector <ll> vll;
typedef vector <ld> vld;
typedef vector <string> vs;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
typedef vector <vi > vvi;
typedef vector <vll > vvll;
typedef vector <pii > vpii;
typedef vector <pll > vpll;

const int N = 2e5 + 5;
int mod = 1e9 + 7, mod1 = 998244353, mod2 = 1e9 + 9, inf = 1e9 + 7;
ll infll = 1e18 + 7;

int binpow(int x, int y){
    int ans = 1;
    while (y){
        if (y & 1) ans = ans * x % mod;
        x = x * x % mod;
        y >>= 1;
    }
    return ans;
}

int n, k, ans = 1, mxall = -infll;
int a[N];
int mnpos = -1, mxpos = -1, mnneg = 1, mxneg = 1;

bool cmp(int x, int y){
    return abs(x) < abs(y);
}

signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    cin >> n >> k;
    ForE(i, 1, n){
        cin >> a[i];
        mxall = max(mxall, a[i]);
    }
    sort(a + 1, a + 1 + n, cmp);
    if (mxall < 0 && k % 2 == 1){
        ForE(i, 1, k){
            ans = ans * a[i] % mod; if (ans < 0) ans += mod;
        }
        cout << ans;
        return 0;
    }
    reverse(a + 1, a + 1 + n);
    ForE(i, 1, k){
        ans = ans * a[i] % mod;
    }
    if (ans >= 0) Ptest(ans);
    else if (k == n){
        if (ans < 0) ans += mod;
        cout << ans;
        return 0;
    }
    ForE(i, 1, k){
        if (a[i] > 0){
            mnpos = a[i];
        }
        if (a[i] < 0){
            mxneg = a[i];
        }
    }
    ForE(i, k + 1, n){
        if (a[i] > 0){
            if (mxpos == -1) mxpos = a[i];
        }
        if (a[i] < 0){
            if (mnneg == 1) mnneg = a[i];
        }
    }
    // cout << mnpos << ' ' << mxneg << ' ' << mxpos << ' ' << mnneg << endl;
    int kek;
    if (mnpos != -1 && mnneg != 1 && mxpos != -1 && mxneg != 1){
        if (mnneg * mxneg < mnpos * mxpos){
            kek = mxpos * binpow(mxneg, mod - 2);
        }
        else{
            kek = mnneg * binpow(mnpos, mod - 2);
        }
    }
    else if (mnpos != -1 && mnneg != 1){
        kek = mnneg * binpow(mnpos, mod - 2);
    }
    else{
        kek = mxpos * binpow(mxneg, mod - 2);
    }
    ans = ans * kek % mod; if (ans < 0) ans += mod;
    cout << ans;
}

/*
==================================+
INPUT:                            |
------------------------------    |

------------------------------    |
==================================+
OUTPUT:                           |
------------------------------    |

------------------------------    |
==================================+
*/

Compiler output:
a.cc: In function 'int main()':
a.cc:125:5: error: 'else' without a previous 'if'
  125 |     else if (k == n){
      |     ^~~~