poj1258

简单题

View Code

   
     

    
      #include 
    
      <
    
      iostream
    
      >
    
      
#include 
    
      <
    
      cstdio
    
      >
    
      
#include 
    
      <
    
      cstdlib
    
      >
    
      
#include 
    
      <
    
      cstring
    
      >
    
      

    
      using
    
       
    
      namespace
    
       std;


    
      #define
    
       inf 0x3f3f3f3f
    
      

    
      #define
    
       maxn 105
    
      


    
      int
    
       vis[maxn];

    
      int
    
       lowc[maxn];

    
      int
    
       cost[maxn][maxn];

    
      int
    
       n;


    
      void
    
       input()
{
 
    
      for
    
       (
    
      int
    
       i 
    
      =
    
       
    
      0
    
      ; i 
    
      <
    
       n; i
    
      ++
    
      )
 
    
      for
    
       (
    
      int
    
       j 
    
      =
    
       
    
      0
    
      ; j 
    
      <
    
       n; j
    
      ++
    
      )
 scanf(
    
      "
    
      %d
    
      "
    
      , 
    
      &
    
      cost[i][j]);
}


    
      int
    
       prim()
{
 
    
      int
    
       i, j, p;
 
    
      int
    
       minc, res 
    
      =
    
       
    
      0
    
      ;
 memset(vis, 
    
      0
    
      , 
    
      sizeof
    
      (vis));
 vis[
    
      0
    
      ] 
    
      =
    
       
    
      1
    
      ;
 
    
      for
    
       (i 
    
      =
    
       
    
      0
    
      ; i 
    
      <
    
       n; i
    
      ++
    
      )
 lowc[i] 
    
      =
    
       cost[
    
      0
    
      ][i];
 
    
      for
    
       (i 
    
      =
    
       
    
      1
    
      ; i 
    
      <
    
       n; i
    
      ++
    
      )
 {
 minc 
    
      =
    
       inf;
 p 
    
      =
    
       
    
      -
    
      1
    
      ;
 
    
      for
    
       (j 
    
      =
    
       
    
      0
    
      ; j 
    
      <
    
       n; j
    
      ++
    
      )
 
    
      if
    
       (
    
      0
    
       
    
      ==
    
       vis[j] 
    
      &&
    
       minc 
    
      >
    
       lowc[j])
 {
 minc 
    
      =
    
       lowc[j];
 p 
    
      =
    
       j;
 }
 
    
      if
    
       (inf 
    
      ==
    
       minc)
 
    
      return
    
       
    
      -
    
      1
    
      ;
 res 
    
      +=
    
       minc;
 vis[p] 
    
      =
    
       
    
      1
    
      ;
 
    
      for
    
       (j 
    
      =
    
       
    
      0
    
      ; j 
    
      <
    
       n; j
    
      ++
    
      )
 
    
      if
    
       (
    
      0
    
       
    
      ==
    
       vis[j] 
    
      &&
    
       lowc[j] 
    
      >
    
       cost[p][j])
 lowc[j] 
    
      =
    
       cost[p][j];
 }
 
    
      return
    
       res;
}


    
      int
    
       main()
{
 
    
      //
    
      freopen("t.txt", "r", stdin);
    
      

    
       
    
      while
    
       (scanf(
    
      "
    
      %d
    
      "
    
      , 
    
      &
    
      n) 
    
      !=
    
       EOF)
 {
 input();
 printf(
    
      "
    
      %d\n
    
      "
    
      , prim());
 }
 
    
      return
    
       
    
      0
    
      ;
}