WA on #1 #6 #8 #10的第一组数据 代码

#include <bits/stdc++.h>
using namespace std;

int T, n, m, vis[1005];
vector<int> e[1005];

void dfs(int u) {
	vis[u] = 1;
	for (int v : e[u]) {
		if (!vis[v]) {
			dfs(v);
		}
	}
	return;
}

bool check() {
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= n; j++) {
			vis[j] = 0;
		}
		dfs(i);
		for (int j = 1; j <= n; j++) {
			if (!vis[j]) {
				return 0;
			}
		}
	}
	return 1;
}

int main() {
	cin >> T;
	while (T--) {
		cin >> n >> m;
		for (int i = 1; i <= n; i++) {
			e[i].clear();
		}
		for (int i = 1; i <= m; i++) {
			int u, v;
			cin >> u >> v;
			e[u].push_back(v);
		}
		if (check()) {
			cout << "Yes" << endl;
		} else {
			cout << "No" << endl;
		}
	}
	return 0;
}