hoj1878

看是否所有定点的度都是偶数，并使用并查集看图是否连通。我开始因为没有判断是否连通而错了许多次。

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

#define maxn 1005

int n, m, f[maxn], father[maxn];

int getanc(int a)
{
    if (father[a] == a)
        return a;
    return father[a] = getanc(father[a]);
}

bool ok()
{
    for (int i = 0; i < n; i++)
        if (f[i] % 2 != 0 || getanc(i) != getanc(0))
            return false;
    return true;
}

int main()
{
    //freopen("D:\\t.txt", "r", stdin);
    while (scanf("%d", &n) != EOF && n != 0)
    {
        scanf("%d", &m);
        for (int i = 0; i < n; i++)
            father[i] = i;
        memset(f, 0, sizeof(f));
        for (int i = 0; i < m; i++)
        {
            int a, b;
            scanf("%d%d", &a, &b);
            a--;
            b--;
            father[getanc(a)] = getanc(b);
            f[a]++;
            f[b]++;
        }
        if (ok())
            printf("1\n");
        else
            printf("0\n");
    }
    return 0;
}