代码

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

评测结果