P1892 团伙

朴素并查集

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<vector>
#include<queue>
using namespace std;
int n,m;
vector <int> dr[1001];
int py[1001];
int findpy(int x)
{
    if(py[x]==x) return x;
    return py[x]=findpy(py[x]);
}
int main()
{
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++)
      py[i]=i;
    for(int i=1;i<=m;i++)
    {
        int x,y;char p;
        cin>>p;
        scanf("%d%d",&x,&y);

        if(p=='F')
         if(findpy(x)!=findpy(y)) 
          py[findpy(y)]=findpy(x);
        else{
            dr[y].push_back(x);
            dr[x].push_back(y);//  双向 
        }
    }

    for(int i=1;i<=n;i++)
    {
        for(int j=0;j<dr[i].size();j++)
           py[findpy(dr[i][j])]=findpy(dr[i][0]);
    }

    int ans=0;
    for(int i=1;i<=n;i++)
     if(findpy(i)==i) ans++;

    printf("%d",ans);
    return 0;
}

反集

#include<iostream> 
#include<cstdio>
#include<cstring>
#include<string>
#include<cmath>
#include<queue>
#include<vector>
#include<algorithm>
using namespace std;
int f[3000];
int find(int u)
{
    //if(f[x]==x) return x;
    //return f[x]=find(f[x]);

    while(f[u]!=u)
    {
        u=f[u];
    }
    return f[u];
}
int main()
{
    int n,m; 
    scanf("%d%d",&n,&m);
    for(int i=1;i<=2*n;i++) f[i]=i;
    for(int i=1;i<=m;i++)
    {
        int x,y;char p;
        cin>>p;
        scanf("%d%d",&x,&y);

        if(p=='F')
           if(find(x)!=find(y)) 
             f[find(x)]=find(y);
        if(p=='E'){//else 不可以，匹配到最近的if
            if(find(x)!=find(y+n))
              f[find(y+n)]=find(x);
            if(find(x+n)!=find(y))
              f[find(x+n)]=find(y);
        }
    }
    int ans=0;
    for(int i=1;i<=n;i++)
     //printf("%d ",f[i]);
     if(f[i]==i)      ans++;
    printf("%d",ans);
    return 0;
}