图论——并查集

/*并查集模板by：mfcheer*/#include <iostream>  #include <cstdio>  #include <string>  #include <cstring>  #include <cstdlib>  #include <algorithm>  #include <vector>  #include <set>  #include <map>  using namespace std;#define N 100010int n, m;int fa[N];int findd(int x){if (fa[x] == -1)return x;elsereturn fa[x] = findd(fa[x]);}void un(int x, int y){int fx = findd(x);int fy = findd(y);if (fx == fy)return;fa[fx] = fy;}int main(){memset(fa, -1, sizeof(fa));while (cin >> n >> m){un(n,m);}return 0;}