poj2726

按c排序，c相同则按d排序（均从小到大），从左至右遍历，当发现一个的d比前面出现过的最小的d还小那么它一定是解。

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

    
      using
    
       
    
      namespace
    
       std;


    
      #define
    
       maxn 10005
    
      


    
      struct
    
       Hotel
{
 
    
      int
    
       c, d;
} f[maxn];


    
      int
    
       n, ans;


    
      bool
    
       
    
      operator
    
       
    
      <
    
      (
    
      const
    
       Hotel 
    
      &
    
      a, 
    
      const
    
       Hotel 
    
      &
    
      b)
{
 
    
      if
    
       (a.c 
    
      ==
    
       b.c)
 
    
      return
    
       a.d 
    
      <
    
       b.d;
 
    
      return
    
       a.c 
    
      <
    
       b.c;
}


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


    
      void
    
       work()
{
 ans 
    
      =
    
       
    
      0
    
      ;
 
    
      int
    
       maxd 
    
      =
    
       
    
      100000000
    
      ;
 
    
      for
    
       (
    
      int
    
       i 
    
      =
    
       
    
      0
    
      ; i 
    
      <
    
       n; i
    
      ++
    
      )
 
    
      if
    
       (f[i].d 
    
      <
    
       maxd)
 {
 ans
    
      ++
    
      ;
 maxd 
    
      =
    
       f[i].d;
 }
}


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

    
       
    
      while
    
       (scanf(
    
      "
    
      %d
    
      "
    
      , 
    
      &
    
      n) 
    
      !=
    
       EOF 
    
      &&
    
       n 
    
      !=
    
       
    
      0
    
      )
 {
 input();
 sort(f, f 
    
      +
    
       n);
 work();
 printf(
    
      "
    
      %d\n
    
      "
    
      , ans);
 }
 
    
      return
    
       
    
      0
    
      ;
}