poj3615

floyd水题，将map[i][j]理解为从i到j的路径中高度最小即可，将松弛条件改为map[i][j]=MIN(map[i][j],MAX(map[i][k],map[k][j]));好好理解一下吧

#include <stdio.h>
#include <string.h>
#define MAXN 310
#define INF (1<<29)
#define MIN(a,b) ((a)<(b)?(a):(b))
#define MAX(a,b) ((a)>(b)?(a):(b))
int n,m,t;
int map[MAXN][MAXN];
void floyd()
{
    for(int k=1;k<=n;++k)
        for(int i=1;i<=n;++i)
            for(int j=1;j<=n;++j)
                map[i][j]=MIN(map[i][j],MAX(map[i][k],map[k][j]));
}
int main()
{
    while(scanf("%d %d %d",&n,&m,&t)==3)
    {
        int a,b,c;
        for(int i=1;i<=n;++i)
            for(int j=1;j<=n;map[i][j++]=INF);
        for(int i=0;i<m;++i)
        {
            scanf("%d %d %d",&a,&b,&c);
            map[a][b]=c;
        }
        floyd();
        for(int i=0;i<t;++i)
        {
            scanf("%d %d",&a,&b);
            if(map[a][b]==INF) printf("-1\n");
            else printf("%d\n",map[a][b]);
        }
    }
    return 0;
}