http://acm.hdu.edu.cn/showproblem.php?pid=1878

题解：欧拉回路

参考文章：https://blog.csdn.net/weixin_43272781/article/details/88553573

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
#define endl "\n"
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=100000+10;
const int M=100000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m,k,p,l,r,u,v;
int ans,cnt,flag,temp,sum;
int pre[N];
int degree[N];
char str;
struct node{};
int find(int x){return pre[x]==x?x:pre[x]=find(pre[x]);}
bool marge(int u,int v){
    int tu=find(u);
    int tv=find(v);
    if(tu!=tv){
        pre[tu]=tv;
        return 0;
    }else{
        return 1;
    }
}
void init(){
    for(int i=1;i<=n;i++){
       pre[i]=i;
    }
    ans=1;
    memset(degree,0,sizeof(degree));
}
int main()
{
#ifdef DEBUG
	freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
#endif
    //ios::sync_with_stdio(false);
    //cin.tie(0);
    //cout.tie(0);
    //scanf("%d",&t);
    while(~scanf("%d",&n)&&n){
        scanf("%d",&m);
        init();
        for(int i=1;i<=m;i++){
            scanf("%d%d",&u,&v);
            degree[u]++;
            degree[v]++;
            marge(u,v);
        }
        for(int i=1; i<=n; i++)
            if(find(i)!=n||degree[i] & 1 /*degree[i] % 2 == 1*/) {
                ans = 0;
                break;
            }
        cout<<ans<<endl;
    }

#ifdef DEBUG
	printf("Time cost : %lf s\n",(double)clock()/CLOCKS_PER_SEC);
#endif
    //cout << "Hello world!" << endl;
    return 0;
}