【欧拉回路】hdu 1878

判是否是欧拉回路，方法：先判连通性，再判度数是否全是偶数

#include <map>
#include <set>
#include <list>
#include <queue>
#include <deque>
#include <stack>
#include <string>
#include <time.h>
#include <cstdio>
#include <math.h>
#include <iomanip>
#include <cstdlib>
#include <limits.h>
#include <string.h>
#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;

#define LL long long
#define MIN INT_MIN
#define MAX INT_MAX
#define pii pair<int ,int>
#define mp make_pair
#define PI acos(-1.0)
#define FRE freopen("input.txt","r",stdin)
#define FF freopen("output.txt","w",stdout)
#define N 1005
vector<int> v[N];
bool vis[N];
int cnt;
int du[N];
void dfs(int x) {
    int i,j;
    vis[x] = 1;
    for (i = 0 ; i < v[x].size(); i++) {
        int y = v[x][i];
        if (!vis[y]) {
            vis[y] = 1;
            cnt++;
            dfs(y);
        }
    }
}
int main(){
    int n,m;
    while(scanf("%d%d",&n,&m) && n) {
        int i,j;
        for (i = 0 ; i <= n; i++) {
            v[i].clear();
            vis[i] = 0;
            du[i] = 0;
        }
        while(m--) {
            int x,y;
            scanf("%d%d",&x,&y);
            v[x].push_back(y);
            v[y].push_back(x);
            du[x]++;
            du[y]++;
        }
        cnt = 1;
        dfs(1);
        if (cnt == n) {
            bool ok = 1;
            for (i = 1; i <= n; i++) {
                if (!du[i] || (du[i]&1)) {
                    ok = 0;
                    break;
                }
            }
            if (ok) {
                printf("1\n");
            } else printf("0\n");
        } else printf("0\n");
    }
    return 0;
}