[kuangbin带你飞]专题四 最短路练习 POJ 2253 Frogger

 1 /* ***********************************************
 2 Author        :SunYuefeng
 3 Created Time  :2016/10/22 14:18:06
 4 File Name     :A.cpp
 5 ************************************************ */
 6 
 7 #include<cstdio>
 8 #include<iostream>
 9 #include<algorithm>
10 #include<cmath>
11 #include<cstring>
12 #include<string>
13 #include<bitset>
14 #include<map>
15 #include<set>
16 #include<stack>
17 #include<vector>
18 #include<queue>
19 #include<list>
20 #define M(a,b) memset(a,b,sizeof(a))
21 using namespace std;
22 typedef long long ll;
23 const int inf=0x3f3f3f3f;
24 const int maxn=2e2+10;
25 const int mod=1e7+7;
26 int dx[8]= {0,0,1,-1,1,-1,1,-1};
27 int dy[8]= {1,-1,0,0,-1,1,1,-1};
28 
29 int n,m;
30 double way[maxn][maxn];
31 double dis[maxn];
32 bool vis[maxn];
33 
34 struct point{
35     int x,y;
36     double dist(point a){
37         return sqrt((x-a.x)*(x-a.x)+(y-a.y)*(y-a.y));
38     }
39 }pt[maxn];
40 
41 void dijkstra(int x){
42     for(int i=0;i<n;i++){
43         dis[i]=way[0][i];
44         vis[i]=false;
45     }
46     dis[x]=0;
47     for(int i=0;i<n;i++){
48         int k=-1;
49         double min=inf;
50         for(int j=0;j<n;j++){
51             if(!vis[j]&&dis[j]<min){
52                 min=dis[j];
53                 k=j;
54             }
55         }
56         if(k==1) break;
57         vis[k]=true;
58         for(int j=0;j<n;j++){
59             if(!vis[j]&&dis[j]>max(dis[k],way[j][k])){
60                 dis[j]=max(dis[k],way[j][k]);
61             }
62         }
63     }
64     printf("Frog Distance = %.3f\n\n",dis[1]);
65 }
66 
67 int main()
68 {
69     //freopen("in.txt","r",stdin);
70     //freopen("out.txt","w",stdout);
71     int _case=1;
72     while(~scanf("%d",&n)&&n){
73         printf("Scenario #%d\n",_case++);
74         for(int i=0;i<n;i++)
75             for(int j=0;j<n;j++)
76                 way[i][j]=inf;
77         for(int i=0;i<n;i++)
78             scanf("%d%d",&pt[i].x,&pt[i].y);
79         for(int i=0;i<n;i++){
80             for(int j=0;j<n;j++){
81                 if(i==j) continue;
82                 way[i][j]=pt[i].dist(pt[j]);
83                 way[j][i]=pt[i].dist(pt[j]);
84             }
85         }
86         dijkstra(0);
87     }
88     return 0;
89 }