PAT (Advanced Level) 1107. Social Clusters (30)

简单并查集。

#include<cstdio>
#include<cstring>
#include<cmath>
#include<vector>
#include<map>
#include<queue>
#include<stack>
#include<algorithm>
using namespace std;

const int maxn=1000+10;
int fa[maxn];
int num[maxn];
int n;
vector<int>g[maxn],ans;

int f(int x)
{
    if(x!=fa[x]) fa[x]=f(fa[x]);
    return fa[x];
}

int main()
{
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
    {
        int num; scanf("%d:",&num);
        while(num--)
        {
            int hob; scanf("%d",&hob);
            g[hob].push_back(i);
        }
    }

    for(int i=0;i<=n;i++) fa[i]=i;

    for(int i=1;i<=1000;i++)
    {
        if(g[i].size()==0) continue;
        int u=f(g[i][0]);
        for(int j=1;j<g[i].size();j++)
        {
            int v=f(g[i][j]);
            if(u!=v) fa[v]=u;
        }
    }

    for(int i=1;i<=n;i++) f(i);

    memset(num,0,sizeof num);
    for(int i=1;i<=n;i++) num[f(i)]++;
    for(int i=1;i<=n;i++) if(num[i]>0) ans.push_back(num[i]);

    sort(ans.begin(),ans.end());
    printf("%d
",ans.size());
    for(int i=ans.size()-1;i>=0;i--)
    {
        printf("%d",ans[i]);
        if(i>0) printf(" ");
        else printf("
");
    }

    return 0;
}