Language: C++

#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <tuple>
#include <utility>
#include <vector>
#define ll long long
#define itn int
#define endl '\n'
#define co(ans) cout<<ans<<endl
#define COYE cout<<"YES"<<endl
#define COYe cout<<"Yes"<<endl
#define COye cout<<"yes"<<endl
#define CONO cout<<"NO"<<endl
#define CONo cout<<"No"<<endl
#define COno cout<<"no"<<endl
#define FORE(i,a) for(auto &i:a)
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define FFOR(i,a,b) for(int i=(a);i<=(b);++i)
#define REP(i,n)  FOR(i,0,n)
#define RREP(i,n)  FFOR(i,1,n)
#define PB push_back
#define MP make_pair
#define ALL(V) (V).begin(),(V).end()
#define SORT(V) sort((V).begin(),(V).end())
#define REVERSE(V) reverse((V).begin(),(V).end())
#define EACH(V,i) for(typeof((V).begin()) i=(V).begin();i!=(V).end();++i)
#define equals(a,b) (fabs((a)-(b))<EPS)
#define INF ((1LL<<62)-(1LL<<31))
#define EPS 1e-10
#define PI 3.141592653589793238
#define MOD 1000000007
#define MAX 5100000
using namespace std;
using Edge=pair<int,int>;
using Graph=vector<vector<int>>;
inline int toInt(string s){int v;istringstream sin(s);sin>>v;return v;}
template<class T>inline string toString(T x){ostringstream sout;sout<<x;return sout.str();}
template<class T>bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T &a,const T &b){if(b<a){a=b;return 1;}return 0;}
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;
const int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};
ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
ll lcm(ll a,ll b){return a/gcd(a,b)*b;}

////////// 二項係数(N<=10^7) //////////

ll fac[MAX],finv[MAX],inv[MAX];
// fac[i] i!
// finv[i] i!の逆元
// inv[i] iの逆元

// テーブルを作る前処理
void COMinit(){
  fac[0]=fac[1]=1;
  finv[0]=finv[1]=1;
  inv[0]=0;
  inv[1]=1;
  for(ll i=2; i<MAX; ++i){
    fac[i]=fac[i-1]*i%MOD;
    inv[i]=MOD-inv[MOD%i]*(MOD/i)%MOD;
    finv[i]=finv[i-1]*inv[i]%MOD;
  }
}

// 二項係数計算
ll COM(ll n,ll k){
  if(n<k) return 0;
  if(n<0 || k<0) return 0;
  return fac[n]*(finv[k]*finv[n-k]%MOD)%MOD;
}

//////////////////////////////////////////////////

int main(){
  COMinit();
  ll N,K,ans=1,cnt=0,PLUS=0,MINUS=0;
  cin>>N>>K;
  
  vector<pair<ll,ll>> A;
  REP(i,N){
    ll a;
    cin>>a;
    if(a>=0){
      A.PB(MP(a,0));
      PLUS++;
    }
    else{
      A.PB(MP(-a,1));
      MINUS++;
    }
  }
  SORT(A);
  REVERSE(A);
  
  REP(i,K){
    ans*=A[i].first;
    ans%=MOD;
    cnt+=A[i].second;
  }
  
  if(N==K){
    if(MINUS%2==1) ans*=-1;
    if(ans<0) ans+=MOD;
    co(ans);
    return 0;
  }
  
  if(MINUS==N){
    if(K%2==1){
      ans=1ll;
      SORT(A);
      REP(i,K){
        ans*=A[i].first;
        ans%=MOD;
      }
      ans*=-1;
      ans%=MOD;
      if(ans<0) ans+=MOD;
      co(ans);
      return 0;
    }
    else{
      co(ans);
      return 0;
    }
  }
  
  if(cnt%2==1){
    if(K-cnt==PLUS){
      for(int i=K-1; i>=0; --i){
        if(A[i].second%2==0){
          ans*=inv[A[i].first];
          ans%=MOD;
          ans*=A[K].first;
          ans%=MOD;
          co(ans);
          return 0;
        }
      }
    }
    else if(cnt==MINUS){
      for(int i=K-1; i>=0; --i){
        if(A[i].second%2==1){
          ans*=inv[A[i].first];
          ans%=MOD;
          ans*=A[K].first;
          ans%=MOD;
          co(ans);
          return 0;
        }
      }
    }
    
    co(ans);
    return 0;
  
}

Compiler output:
a.cc: In function 'int main()':
a.cc:182:2: error: expected '}' at end of input
  182 | }
      |  ^
a.cc:99:11: note: to match this '{'
   99 | int main(){
      |           ^