P3367 【模板】并查集

原题链接

并查集模板练手。

递归版本

#include<bits/stdc++.h>
using namespace std;
const int N=1e4+5;
int father[N];
int find(int mid){
    if (father[mid]!=mid){
        father[mid]=find(father[mid]);
    }
    return father[mid];
}
void union_fa(int x,int y){
    father[find(x)]=find(y);
}
int main(){
    int n,m;
    cin>>n>>m;
    for (int i=1;i<=n;i++) father[i]=i;
    for (int i=1;i<=m;i++){
        int z,x,y;
        cin>>z>>x>>y;
        if (z==2) 
            if (find(x)==find(y)) cout<<"Y\n";
            else cout<<"N\n";
        else {
            union_fa(x,y);
        } 
    }
    return 0;
}

非递归版本

#include<bits/stdc++.h>
using namespace std;
const int N=1e4+5;
int father[N],size[N],Stack[N];
int find(int mid){
    int start=0;
    while (father[mid]!=mid){
        Stack[start++]=mid;
        mid=father[mid];
    }
    for (int i=0;i<start;i++) Stack[i]=mid;
    return father[mid];
}
void union_fa(int x,int y){
    father[find(x)]=find(y);
}
int main(){
    int n,m;
    cin>>n>>m;
    for (int i=1;i<=n;i++){
        father[i]=i;
        size[i]=1;
    }
    for (int i=1;i<=m;i++){
        int z,x,y;
        cin>>z>>x>>y;
        if (z==2) 
            if (find(x)==find(y)) cout<<"Y\n";
            else cout<<"N\n";
        else {
            if (size[find(x)]<size[find(y)]){
                union_fa(x,y);
                size[find(y)]+=size[find(x)];
            }
            else{
                union_fa(y,x);
                size[find(x)]+=size[find(y)];
            }
        } 
    }
    return 0;
}