题解 | 欧拉回路

#include <iostream>
#include<vector>
using namespace std;
vector<int>degree;
vector<int>vist;
void dfs(int node,vector<vector<int>>&G){
    if(vist[node])return;
    vist[node]=1;
    for(int i=0;i<G.size();i++){
        if(G[node][i]&&!vist[i])dfs(i,G);
    }
}
bool isconnected(vector<vector<int>>&G){
  int count=0;
    for(int i=0;i<degree.size();i++){
        if(degree[i]!=0&&!vist[i]){
            dfs(i,G);
            count++;
        }//不是孤立点
       // else countg++; 
    }
    if(count>=2)return false;
    return true;
}
int main() {
     int n;
    while(cin>>n&&n){
        int m;
        cin>>m;
        // 用assign重新分配n个0
        degree.assign(n, 0);
        vist.assign(n, 0);
        vector<vector<int>> G(n, vector<int>(n, 0));
        while(m--){
            int x,y;cin>>x>>y;
            degree[x-1]++;degree[y-1]++;//计算度数
            G[x-1][y-1]=1;G[y-1][x-1]=1;
        }
        int flag=0;
        for(int i=0;i<degree.size();i++){
            if(degree[i]%2){flag=1;break;}//看是否满足是偶数的度
        }
         if(isconnected(G)&&!flag)cout<<1<<endl;
         else cout<<0<<endl;
    }
}