HDOJ 1272 小希的迷宮

~~~題目鏈接~~~

code：

#include <stdio.h>
#define N 100002
int flag = 0, max = 0, num[N], rank[N], father[N];
void init()
{
    for(int i = 0; i<N; i++)
    {
        num[i] = 0;
        rank[i] = 0;
        father[i] = i;
    }
}
int find(int x)
{
    if(father[x] != x)
        father[x] = find(father[x]);
    return father[x];
}
void Union(int x, int y)
{
    if(rank[x]>rank[y])
        father[y] = x;
    else
    {
        if(rank[x]==rank[y])
            rank[y]++;
        father[x] = y;
    }
}
void judge()
{
    int i = 0, cnt  = 0;
    for(i = 1; i<=max; i++)
    {
        if(cnt == 0 && father[i] == i && num[i] == 1)
            cnt++;
        else if(cnt == 1 && father[i] == i && num[i] == 1)
        {
            flag = 1;
            return ;
        }
    }
}
int main()
{
    int a = 0, b = 0;
    while(1)
    {
        flag = max = 0;
        init();
        scanf("%d %d", &a, &b);
        if(a+b == -2) break;
        while(a != 0 && b != 0)
        {
            num[a] = num[b] = 1;
            if(a<b) max = b;
            else max = a;
            int fx = find(a), fy = find(b);
            if(fx == fy) flag = 1;
            else Union(fx, fy);
            scanf("%d %d", &a, &b);
        }
        judge();
        if(flag == 0) printf("Yes\n");
        else printf("No\n");
    }
    return 0;
}