(续)二分查找(不用递归)

接着上一篇，其实不用递归进行二分查找也很简单，当时咋就没想起来呢。。

OK废话少说, show me the code

#include <stdio.h>

int binary_search_no_recursion(int a[], int left, int right, int key){
    while(left<=right){ 　　 //attention!!!
        int mid = (left+right)/2;
        if(key > a[mid])
            left = mid + 1; //attention!!!
        else if(key < a[mid])
            right = mid -1; //attention!!!
        else
            return mid;
    }

    return -1;
}

int main(){
    int a[6]={1,2,3,4,5,6};
    
    printf("%d
", binary_search_no_recursion(a, 0, 5, 6));
    printf("%d
", binary_search_no_recursion(a, 0, 5, 8));
    printf("%d
", binary_search_no_recursion(a, 0, 5, 0));

    return 0;    
}

同样要注意下一级的左右区间，要能退出查找的循环