折半查找.cpp

验证歌德巴赫猜想等

#include<stdio.h>
#define N 15
void main()
{
	void bi_search( int[],int ,int );
	int a[100],x,i,n=15;
	printf("请输入数据：\n");
	for(i=0;i<N;i++)
		scanf("%d",&a[i]);
	printf("输入要查找的数据x:\n");
	scanf("%d",&x);
    bi_search(a,n,x);
}

void bi_search(int a[],int n, int x)
{  int mid, top, bot, find;
   top = 0;    bot = n-1;      find = 0;
 do
   { mid =( top + bot ) / 2;
      if( x == a[mid] )
         {  printf("找到了%3d,是 a[%d]",x,mid);
            printf("\n");
            find = 1;     }
      else if( x < a[mid] )  bot = mid - 1;
      else if( x > a[mid] ) top = mid + 1;
    } while( top <= bot && find == 0 );
   if( find == 0 )
       printf("%3d 没有找到",x);
   printf("\n");    }