hdu 1245 Saving James Bond

http://acm.hdu.edu.cn/showproblem.php?pid=1245

 #include <cstdio>
 #include <cstring>
 #include <cmath>
 #include <queue>
 #include <algorithm>
 #define maxn 500
 using namespace std;
 const double inf=99999999.0;

 int n,m;
 double d;
 double g[maxn][maxn];
 double dis[maxn];
 bool vis[maxn];
 int step[maxn*];
 struct node
 {
    int x,y;
 }p[maxn];

 double min(double x,double y)
 {
     if(x>y) return y;
     return x;
 }

 double sqr(int x)
 {
     return x*x;
 }

 double dist(int x1,int y1,int x2,int y2)
 {
     return sqrt(sqr(x1-x2)+sqr(y1-y2));
 }

 void spfa()
 {
     queue<int>q;
     memset(vis,false,sizeof(vis));
     for(int i=; i<=n+; i++)
     {
         dis[i]=inf;
     }
     dis[]=0.0;
     vis[]=true;
     step[]=;
     q.push();
     while(!q.empty())
     {
         int u=q.front(); q.pop();
         vis[u]=false;
         for(int i=; i<=n+; i++)
         {
             if(g[u][i]<=d)
             {
                 if(g[u][i]+dis[u]<dis[i])
                 {
                     dis[i]=dis[u]+g[u][i];
                     step[i]=step[u]+;
                     if(!vis[i])
                     {
                         vis[i]=true;
                         q.push(i);
                     }
                 }
                 else if(g[u][i]+dis[u]==dis[i])
                 {
                     if(step[i]>step[u]+)
                     {
                         step[i]=step[u]+;
                         if(!vis[i])
                         {
                             vis[i]=true;
                             q.push(i);
                         }
                     }
                 }
             }
         }
     }
 }
 int main()
 {
     while(scanf("%d%lf",&n,&d)!=EOF)
     {
         for(int i=; i<=n; i++)
         {
             scanf("%d%d",&p[i].x,&p[i].y);
         }
         for(int i=; i<=n; i++)
         {
             g[i][i]=0.0;
             for(int j=; j<=n; j++)
             {
                 g[i][j]=dist(p[i].x,p[i].y,p[j].x,p[j].y);
             }
         }
         g[][]=0.0;
         for(int i=; i<=n; i++)
         {
             g[i][]=0.0;
             g[][i]=dist(,,p[i].x,p[i].y)-7.5;
         }
         for(int i=; i<=n; i++)
         {
             g[n+][i]=0.0;
             g[i][n+]=min(50.0-fabs((double)p[i].x),50.0-fabs((double)p[i].y));
         }
         g[][n+]=inf;
         spfa();
         if(dis[n+]==inf)
             printf("can't be saved\n");
         else
             printf("%.2lf %d\n",dis[n+],step[n+]);
     }
     return ;
 }