UVA 567 Risk

flyod 就可以 ，N只有20.不过感觉直接BFS好像行？

#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <stack>
#include <queue>
#include <cctype>
#include <cstdio>
#include <string>
#include <vector>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#define LL long long
#define PI 3.1415926535897932626
using namespace std;
int gcd(int a, int b) {return a % b == 0 ? b : gcd(b, a % b);}
#define MAXN 25
const int INF = 0x3f3f3f3f;
int dist[MAXN][MAXN];
int cnt;
void read()
{
    memset(dist,0x3f,sizeof(dist));
    for (int i = 1; i <= cnt; i++)
    {
        int tmp;
        scanf("%d",&tmp);
        dist[1][tmp] = dist[tmp][1] = 1;
    }
    for (int i = 2; i <= 19; i++)
    {
        scanf("%d",&cnt);
        for (int j = 1; j <= cnt; j++)
        {
            int tmp;
            scanf("%d",&tmp);
            dist[i][tmp] = dist[tmp][i] = 1;
        }
    }
}
int main()
{
    //freopen("sample.txt","r",stdin);
    int kase = 1;
    while (scanf("%d",&cnt) != EOF)
    {
        read();
        for (int k = 1; k <= 20; k++)
            for (int i = 1; i <= 20; i++)
              for (int j = 1; j <= 20; j++)
                dist[i][j] = min(dist[i][j],dist[i][k] + dist[k][j]);
        int N;
        scanf("%d",&N);
        printf("Test Set #%d
",kase++);
        for (int i = 1; i <= N; i++)
        {
            int u,v;
            scanf("%d%d",&u,&v);
            printf("%2d to %2d: %d
",u,v,dist[u][v]);
        }
        putchar('
');
    }
    return 0;
}