代码

int binary_search(const unsigned *a, int n, unsigned x)
{
	int l=0,r=n,mid;
    while(l<=r)
	{
        mid=l+r>>1;
        if (a[mid]==x)
        	return mid;
		(a[mid]<x)?(l=mid+1):(r=mid-1);
    }
    return 0;
}

评测结果