CSUOJ 1010: Water Drinking

http://acm.csu.edu.cn/OnlineJudge/problem.php?id=1010

这道题是要我们找到一个队伍的最后一个骆驼的编号，队伍的要求有两点

1. 骆驼数最少

2. 与池塘相连

#include<cstdio>
#include<cstring>
#include<cstdlib>
#define MAXN 100005

int next[MAXN], s[MAXN];
int N, top, k;

int main()
{
    while( scanf( "%d", &N) == 1)
    {
        int n = N;
        top = 0;
        memset( next, -1, sizeof next);
        while( n --)
        {
            int a, b;
            scanf( "%d%d", &a, &b);
            if( a == 0) s[top ++] = b;
            else
                next[a] = b;
        }
        int min = MAXN;
        for( int i = 0; i < top; i ++)
        {
            int ans = 1, t, j;
            j = s[i];
            while( j != -1)
            {
                ans ++;
                t = j;
                j = next[j];

            }
            if( ans < min ) {
                min = ans;
                k = t;
            }
            if( ans == min && t < k)
                k = t;
        }
        printf( "%d\n", k);
    }
    return 0;
}

用并查集没写过...