and check

Smooth project

Use the array f[] to store the parent node of each node, and access the final parent node recursively through find(a). The way of find(b) combines the two trees

#include<stdio.h>
#include<string.h>
int f[1005];int find(int n){if(f[n]==n)return n;elsereturn f[n]=find(f[n]);//注意此处需将find的值赋给f[n]}int main(){int n,m;while(~scanf("%d",&n)&&n){scanf("%d",&m);if(n==0)break;for(int i=0;i<1005;i++)f[i]=i;int tou;for(int i=0;i<m;i++){int sa,sb;scanf("%d %d",&sa,&sb);int a=find(sa),b=find(sb);if(a==b)continue;else {f[a]=b;}}int cnt[1005];memset(cnt,0,sizeof(cnt));for(int i=1;i<=n;i++)


































{
cnt[find(i)]++;
}
int num=0;
for(int i=1;i<=n;i++)
{
if(cnt[i]!=0)num++;
}
printf("%d\n",num-1);
}
return 0;
}