WHU403 可删除并查集

Posted 2020-10-21 zzzc18

我们记录一下每个元素的编号pid[]
删除时，将删除的点编号变为一个先前未出现的值，fa等于他自己

#include<cstdio>
#include<cstring>
#define MAXN 2000000+9
using namespace std;

int fa[MAXN],pid[MAXN];
int n,ans1,ans2;

int Find(int x){
    return fa[x]==x ? x : fa[x]=Find(fa[x]);
}

void merge(int x,int y){
    int xx=Find(x);
    int yy=Find(y);
    fa[xx]=yy;
}

int main(){
    while(scanf("%d",&n)!=EOF){
        ans1=ans2=0;
        int i;
        for(i=0;i<=n;i++){
            fa[i]=i;
            pid[i]=i;
        }
        while(true){
            char opt[2];
            int x,y;
            scanf("%s",opt);
            if(opt[0]==‘e‘)
                break;
            if(opt[0]==‘c‘){
                scanf("%d%d",&x,&y);
                x=pid[x];
                y=pid[y];
                merge(x,y);
            }
            if(opt[0]==‘d‘){
                scanf("%d",&x);
                pid[x]=++n;
                fa[n]=n;
            }
            if(opt[0]==‘q‘){
                scanf("%d%d",&x,&y);
                x=pid[x];
                y=pid[y];
                int xx=Find(x);
                int yy=Find(y);
                if(xx==yy)
                    ans1++;
                else
                    ans2++;
            }
        }
        printf("%d , %d\n",ans1,ans2);
    }
    return 0;
}