#include <stdio.h>

int main() {
int arr[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};//定义一个数组
int k = 7;//为了算法的普遍性可以将代码改为int k = 0;scanf("%d", &k);
	int sz = sizeof(arr) / sizeof(arr[0]);//数组元素个数
	int left = 0;//左边的下标
	int right = sz - 1;//右边的下标
	while (left <= right) {

  int mid = (left + right) / 2;//中间值
  if (arr[mid] > k) {

  	right = mid - 1;

  } else if (arr[mid] < k) {

  	left = mid + 1;

  } else {

  	printf("找到了，下标是：%d\n", mid);

  	break;

  }

	}

	if (left > right) {

  printf("找不到\n");

	}

	return 0;

}