提出 #73725506

---

ソースコード 拡げる

#include <bits/stdc++.h>
using namespace std;
const int MOD = 998244353;
const int N = 200005;
int par[N];

int fnd(int x)
{
    return par[x] == x ? x : par[x] = fnd(par[x]);
}

int main()
{
    int n, m;
    cin >> n >> m;
    vector<int> u(m + 1), v(m + 1);
    for (int i = 1; i <= m; ++i)
    {
        cin >> u[i] >> v[i];
    }
    vector<int> p2(m + 1);
    p2[0] = 1;
    for (int i = 1; i <= m; ++i)
    {
        p2[i] = p2[i - 1] * 2 % MOD;
    }
    for (int i = 1; i <= N; ++i)
        par[i] = i;
    int cnt = n;
    int ans = 0;
    for (int i = m; i >= 1; --i)
    {
        int a = fnd(u[i]), b = fnd(v[i]);
        if (a != b)
        {
            if (cnt > 2)
            {
                par[a] = b;
                --cnt;
            }
            else
            {
                ans = (ans + p2[i]) % MOD;
            }
        }
    }
    cout << ans << endl;
    return 0;
}

提出情報

コンパイルエラー

./Main.cpp: In function 'main':
./Main.cpp:28:16: warning: iteration 200004 invokes undefined behavior [-Waggressive-loop-optimizations]
   28 |         par[i] = i;
      |         ~~~~~~~^~~
./Main.cpp:27:23: note: within this loop
   27 |     for (int i = 1; i <= N; ++i)
      |                     ~~^~~~
./Main.cpp: In function 'main':
./Main.cpp:28:16: warning: iteration 200004 invokes undefined behavior [-Waggressive-loop-optimizations]
   28 |         par[i] = i;
      |                ^
./Main.cpp:27:23: note: within this loop
   27 |     for (int i = 1; i <= N; ++i)
      |                       ^

ジャッジ結果