思路:并查集,最后结果就是块数-1
代码:
#include <iostream> #include <stdio.h> #include <string.h> #include <math.h> #include <stdlib.h> #include <map> #include <set> #include <vector> #include <stack> #include <queue> #include <algorithm> using namespace std; #define mst(a,b) memset(a,b,sizeof(a)) #define eps 10e-10 #define PI acos(-1.0)//3.14159265 const int MAX_ = 1010; const int N = 100010; const int INF = 0x7fffffff; int fa[MAX_], rank[MAX_]; bool vis[MAX_]; int main(){ int n, m, ans, s, t; while(scanf("%d",&n)&&n){ scanf("%d",&m); for(int i = 0; i <= n; ++i){ //rank[i] = 1; fa[i] = i; } while(m--){ scanf("%d%d",&s,&t); int a ,b; a = findfa(s); b = findfa(t); fa[a] = b; } mst(vis,0); ans = 0; for(int i = 1; i <= n; ++i){ int tmp = findfa(i); if(!vis[tmp]){ vis[tmp] = 1; ans++; } } printf("%d\n",ans-1); } return 0; }