http://acm.hdu.edu.cn/showproblem.php?pid=1245
1 #include <cstdio> 2 #include <cstring> 3 #include <cmath> 4 #include <queue> 5 #include <algorithm> 6 #define maxn 500 7 using namespace std; 8 const double inf=99999999.0; 9 10 int n,m; 11 double d; 12 double g[maxn][maxn]; 13 double dis[maxn]; 14 bool vis[maxn]; 15 int step[maxn*4]; 16 struct node 17 { 18 int x,y; 19 }p[maxn]; 20 21 double min(double x,double y) 22 { 23 if(x>y) return y; 24 return x; 25 } 26 27 double sqr(int x) 28 { 29 return x*x; 30 } 31 32 double dist(int x1,int y1,int x2,int y2) 33 { 34 return sqrt(sqr(x1-x2)+sqr(y1-y2)); 35 } 36 37 38 void spfa() 39 { 40 queue<int>q; 41 memset(vis,false,sizeof(vis)); 42 for(int i=0; i<=n+1; i++) 43 { 44 dis[i]=inf; 45 } 46 dis[0]=0.0; 47 vis[0]=true; 48 step[0]=0; 49 q.push(0); 50 while(!q.empty()) 51 { 52 int u=q.front(); q.pop(); 53 vis[u]=false; 54 for(int i=1; i<=n+1; i++) 55 { 56 if(g[u][i]<=d) 57 { 58 if(g[u][i]+dis[u]<dis[i]) 59 { 60 dis[i]=dis[u]+g[u][i]; 61 step[i]=step[u]+1; 62 if(!vis[i]) 63 { 64 vis[i]=true; 65 q.push(i); 66 } 67 } 68 else if(g[u][i]+dis[u]==dis[i]) 69 { 70 if(step[i]>step[u]+1) 71 { 72 step[i]=step[u]+1; 73 if(!vis[i]) 74 { 75 vis[i]=true; 76 q.push(i); 77 } 78 } 79 } 80 } 81 } 82 } 83 } 84 int main() 85 { 86 while(scanf("%d%lf",&n,&d)!=EOF) 87 { 88 for(int i=1; i<=n; i++) 89 { 90 scanf("%d%d",&p[i].x,&p[i].y); 91 } 92 for(int i=1; i<=n; i++) 93 { 94 g[i][i]=0.0; 95 for(int j=1; j<=n; j++) 96 { 97 g[i][j]=dist(p[i].x,p[i].y,p[j].x,p[j].y); 98 } 99 } 100 g[0][0]=0.0; 101 for(int i=1; i<=n; i++) 102 { 103 g[i][0]=0.0; 104 g[0][i]=dist(0,0,p[i].x,p[i].y)-7.5; 105 } 106 for(int i=1; i<=n; i++) 107 { 108 g[n+1][i]=0.0; 109 g[i][n+1]=min(50.0-fabs((double)p[i].x),50.0-fabs((double)p[i].y)); 110 } 111 g[0][n+1]=inf; 112 spfa(); 113 if(dis[n+1]==inf) 114 printf("can't be saved "); 115 else 116 printf("%.2lf %d ",dis[n+1],step[n+1]); 117 } 118 return 0; 119 }