题目链接：染色法判定二分图

#include <iostream>
#include <cstring>
#include <algorithm>using namespace std;const int N = 100010l, M = 200010;int n, m;
int h[N], e[M], ne[M], idx;int color[N];void add(int a, int b)
{e[idx] = b, ne[idx] = h[a], h[a] = idx ++;
}bool dfs(int u, int c)
{color[u] = c;for(int i = h[u]; i != -1; i = ne[i]){int j = e[i];if(!color[j]){if(!dfs(j, 3 - c)){return false;}}else if(color[j] == c) return false;}return true;
}int main()
{cin >> n >> m;memset(h, -1, sizeof h);while(m--){int a, b;cin >> a >> b;add(a, b), add(b, a);}bool flag = true;for(int i = 1; i <= n; i ++){if(!color[i]){// 进行染色if(!dfs(i, 1)){flag = false;break;}}}if(flag) cout << "Yes" << endl;else cout << "No" << endl;return 0;
}