)
染色法判定二分图 (dfs算法)
判断一张图能否被二分染色。
vector<int> vis(n + 1);
auto dfs = [&](auto self, int x, int type) -> void {vis[x] = type;for (auto y : ver[x]) {if (vis[y] == type) {cout << "NO\n";exit(0);}if (vis[y]) continue;self(self, y, 3 - type);}
};
for (int i = 1; i <= n; ++i) {if (vis[i]) {dfs(dfs, i, 1);}
}
cout << "Yes\n";