HDU 1162 Eddy's picture

最小生成树..

  
    

   
     #include 
   
     <
   
     iostream
   
     >
   
     
#include 
   
     <
   
     string
   
     .h
   
     >
   
     
#include 
   
     <
   
     math.h
   
     >
   
     
#include 
   
     <
   
     iomanip
   
     >
   
     

   
     using
   
      
   
     namespace
   
      std;

   
     const
   
      
   
     int
   
      MAXN 
   
     =
   
      
   
     101
   
     ;


   
     struct
   
      point {
 
   
     double
   
      x,y;
};
point p[MAXN];

   
     double
   
      G[MAXN][MAXN];

   
     double
   
      lowcost[MAXN];

   
     int
   
      closest[MAXN];

   
     bool
   
      used[MAXN];

   
     double
   
      cost;


   
     void
   
      PRIM(
   
     int
   
      n){
 cost 
   
     =
   
      
   
     0
   
     ;
 used[
   
     1
   
     ] 
   
     =
   
      
   
     true
   
     ;
 
   
     for
   
     (
   
     int
   
      i 
   
     =
   
      
   
     2
   
     ; i 
   
     <=
   
      n; i
   
     ++
   
     ){
 lowcost[i] 
   
     =
   
      G[
   
     1
   
     ][i];
 closest[i] 
   
     =
   
      
   
     1
   
     ;
 used[i] 
   
     =
   
      
   
     false
   
     ;
 }
 
   
     double
   
      min;
 
   
     int
   
      minIndex;
 
   
     for
   
     (
   
     int
   
      i 
   
     =
   
      
   
     1
   
     ; i 
   
     <
   
      n; i
   
     ++
   
     ){
 min 
   
     =
   
      
   
     32767.0
   
     ;
 
   
     for
   
     (
   
     int
   
      j 
   
     =
   
      
   
     1
   
     ; j 
   
     <=
   
      n; j
   
     ++
   
     ){
 
   
     if
   
     ( 
   
     !
   
     used[j] 
   
     &&
   
      min 
   
     >
   
      lowcost[j] ){
 min 
   
     =
   
      lowcost[j];
 minIndex 
   
     =
   
      j;
 }
 }
 used[minIndex] 
   
     =
   
      
   
     true
   
     ;
 cost 
   
     +=
   
      min;
 
   
     for
   
     (
   
     int
   
      j 
   
     =
   
      
   
     1
   
     ; j 
   
     <=
   
      n;j
   
     ++
   
     ){
 
   
     if
   
     ( 
   
     !
   
     used[j] 
   
     &&
   
      G[minIndex][j] 
   
     <
   
      lowcost[j])
 lowcost[j] 
   
     =
   
      G[minIndex][j];
 }
 }
}


   
     int
   
      main(){
 
   
     int
   
      N;
 
   
     double
   
      x,y,dis;
 
   
     while
   
     (scanf(
   
     "
   
     %d
   
     "
   
     ,
   
     &
   
     N) 
   
     ==
   
      
   
     1
   
     ){
 
   
     for
   
     (
   
     int
   
      i 
   
     =
   
      
   
     1
   
     ; i 
   
     <=
   
      N; i
   
     ++
   
     ){
 scanf(
   
     "
   
     %lf%lf
   
     "
   
     ,
   
     &
   
     p[i].x,
   
     &
   
     p[i].y); 
 }
 memset(G,
   
     0
   
     ,
   
     sizeof
   
     (G));
 
   
     for
   
     (
   
     int
   
      i 
   
     =
   
      
   
     1
   
     ; i 
   
     <=
   
      N; i
   
     ++
   
     )
 
   
     for
   
     (
   
     int
   
      j 
   
     =
   
      
   
     1
   
     ; j 
   
     <=
   
      N; j
   
     ++
   
     )
 G[i][j] 
   
     =
   
      sqrt((p[i].x
   
     -
   
     p[j].x)
   
     *
   
     (p[i].x
   
     -
   
     p[j].x)
   
     +
   
     (p[i].y
   
     -
   
     p[j].y)
   
     *
   
     (p[i].y
   
     -
   
     p[j].y));
 PRIM(N);
 printf(
   
     "
   
     %.2f\n
   
     "
   
     ,cost);
 }
 
   
     return
   
      
   
     0
   
     ;
}