提出 #21588624

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ソースコード 拡げる

#include <atcoder/all>
using namespace atcoder;
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const double pi = 3.14159265359;
const ll INF = 1LL << 60;

ll MOD = 1000000007;

ll solve_pos(int k, const vector<int>& ps, const vector<int>& ns)
{
  int np = ps.size();
  int nn = ns.size();

  ll r = 1;
  int i = 0, j = 0;
  
  while (k > 0){
    if (k >= 2 && np - i >= 2 && nn - j >= 2){
      ll xp = ll(ps[i]) * ll(ps[i+1]);
      ll xn = ll(ns[j]) * ll(ns[j+1]);
      if (xp > xn){
	r *= ps[i]; // ひとつだけ用いるのがミソ
	r %= MOD;
	i++;
	k--;
      } else {
	r *= xn % MOD; // ここの % MOD 必須
	r %= MOD;
	j += 2;
	k -= 2;
      }
    } else if (k >= 2 && nn - j >= 2) {
      r *= ll(ns[j]) * ll(ns[j+1]) % MOD; // ここの % MOD 必須
      r %= MOD;
      j += 2;
      k -= 2;
    } else if (np > i){
      r *= ps[i];
      r %= MOD;
      i++;
      k--;
    } else {
      r = -1;
      break;
    }
  }

  return r;
}

ll solve_neg(int k, const vector<int>& ps, const vector<int>& ns)
{
  vector<int> v(ps.size() + ns.size());
  for (int i = 0; i < ps.size(); i++){ v[i] = ps[i]; }
  for (int i = 0; i < ns.size(); i++){ v[ps.size() + i] = -ns[i]; }
  sort(v.begin(), v.end());
  
  ll r = -1 % MOD;
  for (int i = 0; i < k; i++){
    r *= v[i];
    r = (r%MOD + MOD) % MOD;
  }
  
  return r;
}

int main()
{
  int n, k;
  cin >> n >> k;

  vector<int> ps, ns;
  for (int i = 0; i < n; i++){
    int x;
    cin >> x;
    if (x >= 0) ps.push_back(x);
    else ns.push_back(x);
  }

  sort(ps.begin(), ps.end(), greater<int>());
  sort(ns.begin(), ns.end());

  ll ans_p = solve_pos(k, ps, ns);

  if (ans_p >= 0){
    cout << ans_p << endl;
    return 0;
  }

  ll ans_n = solve_neg(k, ps, ns);
  cout << ans_n << endl;
  return 0;
}

提出情報

コンパイルエラー

./Main.cpp: In function ‘ll solve_neg(int, const std::vector<int>&, const std::vector<int>&)’:
./Main.cpp:56:21: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   56 |   for (int i = 0; i < ps.size(); i++){ v[i] = ps[i]; }
      |                   ~~^~~~~~~~~~~
./Main.cpp:57:21: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   57 |   for (int i = 0; i < ns.size(); i++){ v[ps.size() + i] = -ns[i]; }
      |                   ~~^~~~~~~~~~~

ジャッジ結果