nyoj42一笔画问题

题目链接：http://acm.nyist.net/JudgeOnline/problem.php?pid=42

先用并查集判断图是否连通，如果不连通，直接输出No

如果连通，判断奇数度的顶点的个数是否为0或者2，如果是，输出Yes,反之，输出No

代码：

#include <cstdio>
#include <cstring>

using namespace std;

int n;
int p,q;
int a,b;

int f[1005];

int degree[1005];

int findIt(int x)

{
    return f[x] == x ? x : f[x] = findIt(f[x]);
}

int main()

{
    int n;
    while(~scanf("%d",&n))
    {
        while(n--)
        {
            memset(degree,0,sizeof degree);
            scanf("%d%d",&p,&q);
            for(int i = 1; i <= p; ++i)
                f[i] = i;
            for(int i = 1; i <= q; ++i)
            {
                scanf("%d%d",&a,&b);
                degree[a]++;
                degree[b]++;
                int ta = findIt(a);
                int tb = findIt(b);
                if(ta != tb)
                {
                    f[ta] = tb;
                }
            }
            int cnt = 0;
            for(int i = 1; i <= p; ++i)
                if(f[i] == i)
                    cnt++;
            //printf("cnt = %d\n",cnt);
            if(cnt != 1)
                printf("No\n");
            else
            {
                int cnt1 = 0;
                for(int i = 1; i <= p; ++i)
                    if(degree[i] % 2)
                        cnt1++;
                //printf("cnt1 = %d\n",cnt1);
                if(cnt1 == 0 || cnt1 == 2)
                    printf("Yes\n");
                else
                    printf("No\n");
            }
        }
    }
    return 0;
}