Hud 2120 Ice_cream's world I[并查集]

题目链接：点击打开链接

该题就是判环个数。

#include<stdio.h>const int N=1005;int n,m,father[N],Number;void Init(){    for(int i=0;i<=n;i++)    father[i]=i;    Number=0;}int find(int x){    if(x!=father[x])    father[x]=find(father[x]);    return father[x];}void Uinon(int x,int y){    int a=find(x);    int b=find(y);    if(a!=b) father[a]=b;    else Number++;//判环个数，要了解这个环的意思.}int main(){    while(~scanf("%d%d",&n,&m))    {        Init();        int a,b;        for(int i=1;i<=m;i++)        {            scanf("%d%d",&a,&b);            Uinon(a,b);        }        printf("%d\n",Number);    }}