巧用“異或”

 

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             : j++; ;
                 : i--; ;
                :

 

             : i--; ;
                 : j++; ;
                :

Ascending = a[] > a[] ?  : ;

memset(CopyA, , () * len);

            (order == --
                ++begin; 

 

            (order == ++
                --end; 

    (a[] < a[len - = = 

     order = ;       

    (a[] > a[len - = 

     order = a[] > a[len - ];        

    (order == (begin <(a[begin] + a[end] >-- (a[begin] + a[end] == 
                ++(begin <(a[begin] + a[end] >++ (a[begin] + a[end] == 
                --

 

#include <stdio.h>
#include <stdbool.h>

#define X 31
bool judge(int [], size_t , int ); 

int main( void )
{
  int test[]= { 5,10,21,41,59 } ;//{ 59,41,21,10,5 };
  printf ( "%d%s存在!\n", 
           X ,
           judge( test , sizeof test/sizeof *test, X ) ? "" :"不"
         );
  return 0;
}


bool judge( int a[] , size_t n , int x )
{
   if ( n < 2u )
      return false;

   if ( x == a[0] + a[n-1] )
      return true;

   if ( (x > a[0] + a[n-1]) ^ ( a[0] > a[n-1]) )
       return  judge( a + 1, n - 1 , x )  ;
   
   return  judge( a  , n - 1 , x );
}

bool judge( int a[] , size_t n , int x ) 
{ 
   while ( n > 1u ) 
   { 
      if ( x == a[0] + a[n-1] ) 
         return true ; 
           
      if ( (x > a[0] + a[n-1]) ^ ( a[0] > a[n-1]) ) 
         a ++ ; 
      n -- ; 
   } 
     
   return false ; 
}