HDU 1879 继续畅通工程

基础 Kruskal

  
    

   
     #include 
   
     <
   
     iostream
   
     >
   
     
#include 
   
     <
   
     stdio.h
   
     >
   
     

   
     using
   
      
   
     namespace
   
      std;

   
     const
   
      
   
     int
   
      MAXN 
   
     =
   
      
   
     101
   
     ;


   
     struct
   
      E{
 
   
     int
   
      x,y;
 
   
     int
   
      weight;
};

E edge[MAXN
   
     *
   
     MAXN
   
     /
   
     2
   
     ];

   
     int
   
      G[MAXN][MAXN];

   
     int
   
      father[MAXN];


   
     int
   
      cmp(
   
     const
   
      
   
     void
   
      
   
     *
   
     d1, 
   
     const
   
      
   
     void
   
      
   
     *
   
     d2){
 
   
     return
   
      (
   
     *
   
     (E
   
     *
   
     )d1).weight 
   
     -
   
      (
   
     *
   
     (E
   
     *
   
     )d2).weight;
}


   
     void
   
      makeSet(
   
     int
   
      n){
 
   
     for
   
     (
   
     int
   
      i 
   
     =
   
      
   
     0
   
     ; i 
   
     <=
   
      n;i
   
     ++
   
     )
 father[i] 
   
     =
   
      i;
}


   
     int
   
      find(
   
     int
   
      x){
 
   
     if
   
     (x 
   
     !=
   
      father[x])
 father[x] 
   
     =
   
      find(father[x]);
 
   
     return
   
      father[x];
}


   
     void
   
      merge(
   
     int
   
      x, 
   
     int
   
      y){
 x 
   
     =
   
      find(x);
 y 
   
     =
   
      find(y);
 
   
     if
   
     (x 
   
     >
   
      y)
 father[x] 
   
     =
   
      y;
 
   
     else
   
     
 father[y] 
   
     =
   
      x;
}

   
     int
   
      main(){
 
   
     int
   
      n;
 
   
     int
   
      x,y,weight,statu,cost;
 
   
     while
   
     (cin 
   
     >>
   
      n , n){
 makeSet(n);
 cost 
   
     =
   
      
   
     0
   
     ;
 
   
     for
   
     (
   
     int
   
      i 
   
     =
   
      
   
     1
   
     ; i 
   
     <=
   
      n
   
     *
   
     (n
   
     -
   
     1
   
     )
   
     /
   
     2
   
     ; i
   
     ++
   
     ){
 scanf(
   
     "
   
     %d%d%d%d
   
     "
   
     ,
   
     &
   
     edge[i].x,
   
     &
   
     edge[i].y,
   
     &
   
     edge[i].weight,
   
     &
   
     statu);
 
   
     if
   
     (statu 
   
     ==
   
      
   
     1
   
     ){
 
   
     int
   
      xx 
   
     =
   
      find(edge[i].x);
 
   
     int
   
      yy 
   
     =
   
      find(edge[i].y);
 
   
     if
   
     (xx 
   
     !=
   
      yy)
 merge(xx,yy);
 }
 }
 qsort(edge
   
     +
   
     1
   
     ,n
   
     *
   
     (n
   
     -
   
     1
   
     )
   
     /
   
     2
   
     ,
   
     sizeof
   
     (E),cmp); 
   
     //
   
     edge + 1
   
     

   
      
   
     for
   
     (
   
     int
   
      i 
   
     =
   
      
   
     1
   
     ; i 
   
     <=
   
      n
   
     *
   
     (n
   
     -
   
     1
   
     )
   
     /
   
     2
   
      ;i
   
     ++
   
     ){
 
   
     int
   
      xx 
   
     =
   
      find(edge[i].x);
 
   
     int
   
      yy 
   
     =
   
      find(edge[i].y);
 
   
     if
   
     (xx 
   
     !=
   
      yy){
 merge(xx,yy);
 cost 
   
     +=
   
      edge[i].weight;
 }
 }
 cout 
   
     <<
   
      cost 
   
     <<
   
      endl;
 }
 
   
     return
   
      
   
     0
   
     ;
}