#include<stdio.h>
int find(int arr[],int sz,int k)
{
	int left = 0; int right = sz - 1;

	while (left<=right)
	{
		int mid = left + right / 2;
		if (k>arr[mid])
		{
			left = mid + 1;
		}
		if (k < arr[mid])
		{
			right = mid - 1;
		}
		if(k==arr[mid])
		{
			return mid;
		}
	}
	return -1;
}
int main()
{
	int k = 0;
	printf("请输入要查找的数字");
	scanf("%d", &k);
	int arr[] = { 1,2,3,4,5,6,7,8,9,10 };
	int sz = sizeof(arr) / sizeof(arr[0]);

	int undernumber = find(arr, sz, k);
	if (undernumber==-1)
	{
		printf("没找到!!!");
	}
	else
	{
		printf("找到了 下标为：%d", undernumber);
	}
	return 0;

}