最短路径 一 Dijkstra 模板(O(n^2))

题目传送：http://hihocoder.com/problemset/problem/1081

 #include<iostream>
 #include<cstdio>
 #include<cstring>
 #define INF 0x03F3F3F3F
 #define N 1024
 int path[N], vis[N];
 int cost[N][N],lowcost[N];
 void Dijkstra(int n, int beg){
  int i, j, min;
  memset(vis, , sizeof(vis));
  vis[beg] = ;
  for (i=; i<n; i++)
 {
   lowcost[i] = cost[beg][i]; path[i] = beg;
 }
 lowcost[beg] = ;
 path[beg] = -;   //
 int pre = beg;
 for (i=; i<n; i++){
     min = INF;
     for (j=; j<n; j++)
         if (vis[j]== && lowcost[pre]+cost[pre][j]<lowcost[j])
         {
         lowcost[j] = lowcost[pre] + cost[pre][j];
         path[j] = pre;
         }
     for (j=; j<n; j++)
         if (vis[j] ==  && lowcost[j] < min){
                 min = lowcost[j]; pre = j;
         }
     vis[pre] = ;
  }
 }
 int main(){
     int n,m,s,t,i,k,a,b,c;
     scanf("%d%d%d%d",&n,&m,&s,&t);
     memset(cost,INF,sizeof(cost));
     for(i =  ;i<m;i++){
         scanf("%d%d%d",&a,&b,&c);
         if(c<cost[a-][b-]){
             cost[a-][b-] = c;
             cost[b-][a-] = c;
         }
     }
     Dijkstra(n, s-);
     printf("%d\n",lowcost[t-]);
     return ;
 }