说来惭愧啊。。现在才会并查集。我竟然给我妈妈讲明白并查集怎么回事了- -

 

#define  _CRT_SECURE_NO_WARNINGS#include 
    
     using namespace std;#define maxx 50010int set[maxx];int find(int x) { 	return x == set[x] ? x : (set[x] = find(set[x])); }int main(){	int n, m;	int kase = 0;	while (cin >> n >> m && (n || m))	{		for (int i = 1; i <= n; i++)		{			set[i] = i;		}		for (int i = 0; i < m; i++)		{			int a, b;			scanf("%d %d", &a, &b);			int c = find(a), d = find(b);			if (c != d){ set[c] = d; }		}		int cnt = 0;		for (int i = 1; i <= n; i++)		{			if (set[i] == i) cnt++;		}		cout << "Case " << ++kase << ": " << cnt << endl;	}}