POJ 2352 Stars

解题思路：线段数组求解小于当前点x坐标点的个数

代码

   
     

    
      
    
      #include 
    
      <
    
      iostream
    
      >
    
      

    
      using
    
       
    
      namespace
    
       std;

    
      #define
    
       lowbit(k) (k&(k^(k-1)))
    
      

    
      int
    
       main()
{
 
    
      int
    
       i,n,t,s,maxX,x[
    
      15000
    
      ],y[
    
      15000
    
      ],m[
    
      32002
    
      ]
    
      =
    
      {
    
      0
    
      },level[
    
      15000
    
      ]
    
      =
    
      {
    
      0
    
      };
 scanf(
    
      "
    
      %d
    
      "
    
      , 
    
      &
    
      n);
 
    
      for
    
      (maxX
    
      =
    
      i
    
      =
    
      0
    
      ;i
    
      <
    
      n;i
    
      ++
    
      ){scanf(
    
      "
    
      %d %d
    
      "
    
      ,x
    
      +
    
      i,y
    
      +
    
      i);
    
      if
    
      (x[i]
    
      >
    
      maxX)maxX
    
      =
    
      x[i];}
 
    
      for
    
      (i
    
      =
    
      0
    
      ;i
    
      <
    
      n;i
    
      ++
    
      )
 {
 s
    
      =
    
      0
    
      ,t
    
      =
    
      x[i]
    
      +
    
      1
    
      ;
 
    
      while
    
      (t
    
      >
    
      0
    
      )s
    
      +=
    
      m[t],t
    
      -=
    
      lowbit(t);
 level[s]
    
      ++
    
      ;
 t
    
      =
    
      x[i]
    
      +
    
      1
    
      ;
 
    
      while
    
      (t
    
      <=
    
      maxX
    
      +
    
      1
    
      )m[t]
    
      ++
    
      ,t
    
      +=
    
      lowbit(t);
 }
 
    
      for
    
      (i
    
      =
    
      0
    
      ;i
    
      <
    
      n;i
    
      ++
    
      )printf(
    
      "
    
      %d\n
    
      "
    
      , level[i]);
 
    
      return
    
       
    
      0
    
      ;
}