二分查找的一个版本

 

#include <stdio.h>
#include <stdlib.h>
#define  NUM   100
typedef struct node
{
        int x;
        int y;
}node ;
node  global[NUM]={-999};
int  count=0;
int find(int left,int right,node x)
{
        int  mid =(left +right )/2;
        if (left==mid )
        {  
                 if(  x.x==global [right].x)
                        return  right;
                else  if(  x.x==global [left].x)
                        return  left;
                else
                        return   -1;
        } 
        else if( x.x > global [ mid  ].x  )
                return  find  ( mid  ,right ,x );
        else
                return  find (left ,  mid ,  x);

}

int  main()
{
        int i=0,j=0;
        struct node temp;
        for(i=0;i<NUM;i++)
        {
                j=i*i;
                temp.x=j;
                printf("  (%d)  ",temp.x);
                global[i].x=j;
        }
        printf("\n");
        temp.x=0;
        find ( 0,NUM-1,temp);
        for(i=0;i<NUM;i++)
        {
                temp.x=global[i].x;
                printf("result is  {%d } \n",  find ( 0 , NUM-1 , temp));
        }

        printf("new\n ");

        while ( scanf("%d",&j) && j )
        {
                temp.x=j;
                printf("result is  {%d } \n",  find ( 0 ,NUM-1 , temp));
        }
}