Language: C++

#include <bits/stdc++.h>
const int INF = 1e9;
const int MOD = 1e9+7;
const long long LINF = 1e18;
#define dump(x)  cout << 'x' << ' = ' << (x) << ` `;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n) for(int i=0;i<(n);++i)
#define REPR(i,n) for(int i=n;i>=0;i--)
#define FOREACH(x,a) for(auto& (x) : (a) )
typedef long long ll;
using namespace std;
typedef pair<ll, ll> P;

template<typename T>
void print(const vector<T> &x) {
    int n = x.size();
    rep(i,n) {
        cout << x[i];
        if (i!=n-1) cout<<" ";
        else cout << endl;
    }
}

template<typename T>
void print(const vector<vector<T>> &x) {
    int n = x.size();
    rep(i,n) {
        rep(j,x[i].size()) {
            cout << x[i][j] << " ";
        }
        cout << endl;
    }
}

template<typename T>
void print(const vector<T> &x, int n) {
    rep(i,n) {
        cout << x[i];
        if (i!=n-1) cout<<" ";
        else cout << endl;
    }
}

template<typename T>
void print(const vector<vector<T>> &x, int n, int m) {
    rep(i,n) {
        rep(j,m) {
            cout << x[i][j] << " ";
        }
        cout << endl;
    }
}

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

void input_init() {
    cin.tie(0); ios::sync_with_stdio(false);
}

template< int mod >
struct ModInt {
    int x;

    ModInt() : x(0) {}

    ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}

    ModInt &operator+=(const ModInt &p) {
        if((x += p.x) >= mod) x -= mod;
        return *this;
    }

    ModInt &operator-=(const ModInt &p) {
        if((x += mod - p.x) >= mod) x -= mod;
        return *this;
    }

    ModInt &operator*=(const ModInt &p) {
        x = (int) (1LL * x * p.x % mod);
        return *this;
    }

    ModInt &operator/=(const ModInt &p) {
        *this *= p.inverse();
        return *this;
    }

    ModInt operator-() const { return ModInt(-x); }

    ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }

    ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }

    ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }

    ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }

    bool operator==(const ModInt &p) const { return x == p.x; }

    bool operator!=(const ModInt &p) const { return x != p.x; }

    ModInt inverse() const {
        int a = x, b = mod, u = 1, v = 0, t;
        while(b > 0) {
        t = a / b;
        swap(a -= t * b, b);
        swap(u -= t * v, v);
        }
        return ModInt(u);
    }

    ModInt pow(int64_t n) const {
        ModInt ret(1), mul(x);
        while(n > 0) {
        if(n & 1) ret *= mul;
        mul *= mul;
        n >>= 1;
        }
        return ret;
    }

    friend ostream &operator<<(ostream &os, const ModInt &p) {
        return os << p.x;
    }

    friend istream &operator>>(istream &is, ModInt &a) {
        int64_t t;
        is >> t;
        a = ModInt< mod >(t);
        return (is);
    }

    static int get_mod() { return mod; }
};

using modint = ModInt<MOD>;

int main(int argc, char const *argv[]) {
    ll n,k; cin>>n>>k;
    vector<ll> a(n);
    rep(i,n) cin>>a[i];
    vector<ll> c(a);
    sort(a.begin(), a.end(), [](const ll &l, const ll &r) {
        return abs(l) > abs(r);
    });

    /*
    modint min_num = 0;
    modint pul_num = 0;
    modint zer_num = 0;
    rep(i,n) {
        if (a[i] < 0) min_num+=1;
        else if (a[i] > 0) pul_num+=1;
        else zer_num+=1;
    }
    */

    modint ans = 1;
    int cnt = 0;
    vector<ll> b;
    vector<ll> p;
    rep(i,k) {
        if (a[i] < 0ll) {
            cnt++;
            b.push_back(i);
        }
        else {
            p.push_back(i);
        }
        ans *= a[i];
    }

    if (cnt % 2 == 0) {
        cout << ans << '\n';
        return 0;
    }

    modint ans = 1;
    vector<ll> q(a);
    q[b.back()] = 1;
    rep(i,k) {
        ans *= q[i];
    }

    ll tmp = -1;
    for (int i = n-1; i >= k; --i) {
        chmax(tmp,q[i]);
    }
    if (tmp >= 0) {
        ans *= tmp;
        if (a[b.back()] * a[b.back()+1] < tmp * p.back()) {
            cout << ans << '\n';
            return 0;
        }
        ans = 1;
        rep(i,p.back()) ans *= a[i];
        ans *= a[b.back()]*a[b.back()+1];
        cout << ans << '\n';
        return 0;
    }


    vector<ll> r(a);

    modint ans_tmp2 = 1;


    sort(c.begin(), c.end(), [](const ll &l, const ll &r) {
        return abs(l) < abs(r);
    });

    ans = 1;
    rep(i,k) ans *= c[i];
    cout << ans << '\n';

    return 0;
}

Compiler output:
a.cc: In function 'int main(int, const char**)':
a.cc:179:12: error: redeclaration of 'modint ans'
  179 |     modint ans = 1;
      |            ^~~
a.cc:159:12: note: 'modint ans' previously declared here
  159 |     modint ans = 1;
      |            ^~~