并查集模板

#include <iostream>using namespace std;#define N 100005struct set{int parent;  //记录父节点int rank;    //记录集合的节点数} elem[N];int MAX;void init(){int i;for (i = 0; i <= N; i++){elem[i].parent = i;elem[i].rank = 1;}}int Find(int x){int root, temp;temp = x;while (x != elem[x].parent) //寻找根节点{x = elem[x].parent;}root = x;x = temp;while (x != elem[x].parent) //压缩路径，全部赋值为根节点的值{temp = elem[x].parent;elem[x].parent = root;x = temp;}return root;}void Union(int a, int b)  //合并两个集合{int x, y;x = Find(a);y = Find(b);if (elem[x].rank >= elem[y].rank){elem[y].parent = elem[x].parent;elem[x].rank += elem[y].rank;if (MAX < elem[x].rank){MAX = elem[x].rank;}}else{elem[x].parent = elem[y].parent;elem[y].rank += elem[x].rank;if (MAX < elem[y].rank){MAX = elem[y].rank;}}}int main(){int n;  //有关系的对数int a, b, x, y;while (scanf("%d", &n) != EOF){init();MAX = -1;while (n--){scanf("%d%d", &a, &b);x = Find(a);y = Find(b);if (x != y){Union(a, b);    //a和b不是一个集合的，合并这两个集合}}if (MAX != -1){printf("%d/n", MAX);    //输出最大集合的节点数}else{printf("1/n");    //此时n=0，证明都是没关系的人}}return 0;}