最短路径问题(floyd)

http://acm.sdut.edu.cn/sdutoj/problem.php?action=showproblem&problemid=1867

 #include<stdio.h>
 #include<string.h>
 #include<math.h>
 const int maxn = ;
 const int INF=<<;
 double dis[maxn][maxn];
 struct node
 {
     double x;
     double y;
 } f[maxn];//储存每个点的坐标
 int n,m;
 void init()
 {
     for (int i = ; i <= n; i ++)
     {
         for (int j = ; j <= n; j ++)
         {
             dis[i][j] = INF;
         }
         dis[i][i] = ;
     }
 }
 void floyd()
 {
     int i,j,k;
     for (k = ; k <= n; k ++)
     {
         for (i = ; i <= n; i ++)
         {
             for (j = ; j <= n; j ++)
             {
                 if(dis[i][j] > dis[i][k] + dis[k][j])//更新距离
                     dis[i][j] = dis[i][k] + dis[k][j];
             }
         }
     }
 }
 int main()
 {
     scanf("%d",&n);
     init();
     for (int i = ; i <= n; i ++)
     {
         scanf("%lf%lf",&f[i].x,&f[i].y);
     }
     scanf("%d",&m);
     int u,v;
     while(m--)
     {
         scanf("%d%d",&u,&v);
         double d = sqrt((f[u].x-f[v].x)*(f[u].x-f[v].x)+(f[u].y-f[v].y)*(f[u].y-f[v].y));//计算u、v 之间的距离
         if (dis[u][v] > d) // 判断重边
         {
             dis[u][v] = d;
             dis[v][u] = d;
         }
     }
     int s,e;
     scanf("%d%d",&s,&e);
     floyd();
     printf("%.2f\n",dis[s][e]);
     return ;
 }