并查集——A1107.Social Clusters(30)

#include <bits/stdc++.h>
#include <stdio.h>
#include <stdlib.h>
#include <queue>
using namespace std;
const int N = 1010;
int father[N];
int isRoot[N] = {0};
int course[N] = {0};
int findFather(int x){
    int a = x;
    while(x != father[x]){
        x = father[x];
    }
    //路径压缩
    while(a != father[a]){
        int z = a;
        a = father[a];
        father[z] = x;
    }
    return x;
}
void Union(int a,int b){
    int faA = findFather(a);
    int faB = findFather(b);
    if(faA != faB){
        father[faA] = faB;
    }
}
void init(int n){
    for(int i=1;i<=n;++i){
        father[i] = i;
        isRoot[i] = false;
    }
}
bool cmp(int a,int b){
    return a > b;
}
int main(){
    int n,k,h;
    scanf("%d",&n);
    init(n);
    for(int i=1;i<=n;++i){
        scanf("%d",&k);
        for(int j = 0;j<k;++j){
            scanf("%d",&h);
            if(course[h] == 0){
                course[h] = i;
            }
            Union(i,findFather(course[h]));
        }
    }
    for(int i=1;i<=n;++i){
        isRoot[findFather(i)]++;
    }
    int ans = 0;
    for(int i=1;i<=n;++i){
        if(isRoot[i] != 0){
            ans++;
        }
    }
    printf("%d
",ans);
    sort(isRoot+1,isRoot+n+1,cmp);
    for(int i=1;i<=ans;++i){
        printf("%d",isRoot[i]);
        if(i < ans){
            printf(" ");
        }
    }
    
    system("pause");
    return 0;
}