题解 | 欧拉回路

#include<iostream>
using namespace std;
const int maxn=1000;
int father[maxn];
int degree[maxn];
int height[maxn];
void initial(int n){
    for(int i=1;i<=n;i++){
        father[i]=i;
        degree[i]=0;
        height[i]=0;
    }
}
int find(int x){
    if(x!=father[x]){
        father[x]=find(father[x]);
    }
    return father[x];
}
void Union(int x,int y){
    x=find(x);
    y=find(y);
    if(x!=y){
        if(height[x]<height[y]){
            father[x]=y;
        }
        else if(height[x]>height[y]){
            father[y]=x;
        }
        else{
            father[y]=x;
            height[x]++;
        }
    }
}
int main(){
    int n,m;
    while(cin>>n){
        if(n==0){
            break;
        }
        cin>>m;
        initial(n);
        for(int i=0;i<m;i++){
            int from,to;
            cin>>from>>to;
            if(from==to){
                continue;
            }
            degree[from]++;
            degree[to]++;
            if(find(from)!=find(to)){
                Union(from,to);
            }
        }
        int flag=1;
        for(int i=1;i<=n;i++){
            if(degree[i]%2!=0){
                flag=0;
            }
        }
        for(int i=2;i<=n;i++){
            if(find(i)!=find(1)&&find(i)!=i){
                flag=0;
            }
        }
        cout<<flag<<endl;
    }
}