最短路径算法之二——Dijkstra算法

 1 #include<stdio.h>
 2 #include<limits.h>
 3 #include<iostream>
 4 #include<string.h>
 5 #define MAXN 200
 6 using namespace std;
 7 int edge[MAXN+10][MAXN+10];
 8 int dis[MAXN+10];
 9 bool vis[MAXN+10];
10 int T,S,D,N,k;
11 void dijkstra(int begin)
12 {
13     memset(vis,0,sizeof(vis));
14     for (int i=1; i<=T; i++)
15         dis[i]=INT_MAX;
16     dis[begin]=0;
17     for (int t=1; t<=T; t++)
18     {
19         vis[begin]=1;
20         for (int i=1; i<=T; i++)
21             if (!vis[i]&&edge[begin][i]!=INT_MAX&&dis[begin]+edge[begin][i]<dis[i])
22                 dis[i]=dis[begin]+edge[begin][i];
23         int min=INT_MAX;
24         for (int j=1; j<=T; j++)
25             if (!vis[j]&&min>dis[j])
26             {
27                 min=dis[j];
28                 begin=j;
29             }
30     }
31 }
32 int main()
33 {
34     int begin,end;
35     while (cin>>T)
36     {
37         if (T==0) break;
38         for (int i=1; i<=MAXN; i++)
39             for (int j=1; j<=MAXN; j++)
40                 edge[i][j]=INT_MAX;
41         scanf("%d %d",&begin,&end);
42         int t;
43         for (int i=1; i<=T; i++)
44         {
45             scanf("%d",&t);
46             if (i+t<=T) edge[i][i+t]=1;
47             if (i-t>=1) edge[i][i-t]=1;
48         }
49         dijkstra(begin);
50         if (dis[end]!=INT_MAX) printf("%d\n",dis[end]);
51         else printf("-1\n");
52     }
53     return 0;
54 }