POJ 2485 Highways

解题思路:Prim算法求解最小生成树，

  
    

   
     
   
     #include
   
     <
   
     iostream
   
     >
   
     

   
     using
   
      
   
     namespace
   
      std;


   
     #define
   
      MaxNum 1e8
   
     


   
     int
   
      main()
{
 
   
     int
   
      m, n, min, start, tempS, MinMax;
 
   
     int
   
      edge[
   
     505
   
     ][
   
     505
   
     ];
 
   
     int
   
      dist[
   
     505
   
     ];
 
   
     int
   
      path[
   
     505
   
     ];
 
   
     bool
   
      visited[
   
     505
   
     ];
 scanf(
   
     "
   
     %d
   
     "
   
     , 
   
     &
   
     m);
 
   
     while
   
      (m
   
     --
   
     )
 {
 scanf(
   
     "
   
     %d
   
     "
   
     , 
   
     &
   
     n);

 dist[
   
     0
   
     ] 
   
     =
   
      
   
     0
   
     ;
 start 
   
     =
   
      
   
     0
   
     ;
 path[
   
     0
   
     ] 
   
     =
   
      
   
     0
   
     ;

 fill(
   
     &
   
     dist[
   
     1
   
     ], 
   
     &
   
     dist[n], MaxNum);
 fill(
   
     &
   
     path[
   
     1
   
     ], 
   
     &
   
     path[n], 
   
     -
   
     1
   
     );
 memset(visited, 
   
     0
   
     , 
   
     sizeof
   
     (
   
     bool
   
     ) 
   
     *
   
      
   
     505
   
     );

 
   
     for
   
      (
   
     int
   
      i 
   
     =
   
      
   
     0
   
     ; i 
   
     <
   
      n; i
   
     ++
   
     )
 
   
     for
   
      (
   
     int
   
      j 
   
     =
   
      
   
     0
   
     ; j 
   
     <
   
      n; j
   
     ++
   
     )
 scanf(
   
     "
   
     %d
   
     "
   
     , 
   
     &
   
     edge[i][j]);

 
   
     while
   
      (start 
   
     !=
   
      
   
     -
   
     1
   
     )
 {
 visited[start] 
   
     =
   
      
   
     true
   
     ;
 tempS 
   
     =
   
      
   
     -
   
     1
   
     ;
 min 
   
     =
   
      MaxNum;

 
   
     for
   
      (
   
     int
   
      i 
   
     =
   
      
   
     0
   
     ; i 
   
     <
   
      n; i
   
     ++
   
     )
 {
 
   
     if
   
      (
   
     !
   
     visited[i])
 {
 
   
     if
   
      (dist[i] 
   
     >
   
      edge[start][i])
 {
 dist[i] 
   
     =
   
      edge[start][i];
 path[i] 
   
     =
   
      start;
 }
 
   
     if
   
      (min 
   
     >
   
      dist[i])
 {
 min 
   
     =
   
      dist[i];
 tempS 
   
     =
   
      i;
 }
 }
 }
 start 
   
     =
   
      tempS;
 }
 MinMax 
   
     =
   
      
   
     0
   
     ;
 
   
     for
   
      (
   
     int
   
      i 
   
     =
   
      
   
     0
   
     ; i 
   
     <
   
      n; i
   
     ++
   
     )
 
   
     if
   
      (MinMax 
   
     <
   
      edge[path[i]][i])
 MinMax 
   
     =
   
      edge[path[i]][i];
 printf(
   
     "
   
     %d\n
   
     "
   
     , MinMax);
 }
 
   
     return
   
      
   
     0
   
     ;
}