NYIST OJ 题目42 一笔画问题

水题。无向图欧拉通路的判定。用并查集判定是不是连通图！

#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;
 
const int maxn =  + ;
int tott[maxn];
int father[maxn];
 
int find(int x)
{
    if (x != father[x]) father[x] = find(father[x]);
    return father[x];
}
 
int main()
{
    int T;
    scanf("%d", &T);
    while (T--)
    {
        int i, n, m, u, v;
        scanf("%d%d", &n, &m);
        for (i = ; i <= n; i++) father[i] = i;
        memset(tott, , sizeof(tott));
        for (i = ; i < m; i++)
        {
            scanf("%d%d", &u, &v);
            int fu = find(u);
            int fv = find(v);
            if (fu != fv) father[fu] = fv;
            tott[u]++;
            tott[v]++;
        }
        int ji = , ou = ;
        for (i = ; i <= n; i++)
        {
            if (tott[i] == ) continue;
            if (tott[i] %  == ) ou++;
            else ji++;
        }
        int jieguo = ;
        int th = find();
        for (i = ; i <= n; i++)
        {
            int tg = find(i);
            if (tg != th) break;
        }
        if (i == n + ) jieguo = ;
        if (jieguo == )
        {
            if (ji ==  || ji == ) jieguo = ;
            else jieguo = ;
        }
        if (jieguo == ) printf("Yes\n");
        else printf("No\n");
    }
    return ;
}