HDU1598-find the most comfortable road

http://acm.hdu.edu.cn/showproblem.php?pid=1598

#include<iostream>
#include<cstdio>
#include<cstdlib>
#define INF 10000000
#define N 1000
using namespace std;
int n,m;
struct Edge 
{
    int s,t,w;
}edge[N+10];
int fa[205];
int cmp(const void *f1,const void *f2)
{
    return (*(struct Edge *)f1).w-(*(struct Edge *)f2).w;
}
int find(int x)
{
    return fa[x]==x?x:fa[x]=find(fa[x]);
}
int main(void)
{
    int i,j,Q,s,e,min,x,y;
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        for(i=0;i<m;i++)
           scanf("%d%d%d",&edge[i].s,&edge[i].t,&edge[i].w);
        qsort(edge,m,sizeof(edge[0]),cmp);
        scanf("%d",&Q);
        while(Q--)
        {
            scanf("%d%d",&s,&e);
            min=INF;
            for(i=0;i<m;i++)
            {
                for(j=0;j<=n;j++)
                   fa[j]=j;
                for(j=i;j<m;j++)
                {
                   x=find(edge[j].s);
                   y=find(edge[j].t);
                   if(x!=y)
                      fa[x]=y;
                   if(find(s)==find(e))
                   {
                      min=min>edge[j].w-edge[i].w?edge[j].w-edge[i].w:min;
                      break;
                   }

                }
            }
            if(min!=INF)
               printf("%d\n",min);
            else 
               printf("-1\n");
        }
    }
    return 0;
}