HDU 1232

并查集水题：

#include <cstdio>#include <cstring>#define LEN 1001int p[LEN];void init(int len) {for(int i = 0; i <= len; i++) {p[i] = i;}}int find(int x) {return p[x] == x ? x : (p[x] = find(p[x]));}int main() {int n, m, a, b;int i, j;int sum;while(scanf("%d%d", &n, &m), n != 0) {sum = 0;init(n);for(i = 0; i < m; i++) {scanf("%d%d", &a, &b);int t1 = find(p[a]);int t2 = find(p[b]);if(t1 != t2) {p[t1] = t2;}}for(i = 1; i <= n; i++) {if(p[i] == i) {++sum;}}printf("%d\n", sum-1);}return 0;}