#include <stdio.h>int binsearch(int x, int v[], int n){ int left = 0; int right = n - 1; while (left <= right) { int mid = (left + right)/2; if (v[mid] < x) { left = mid + 1; } else if (v[mid] == x) { return mid; } else { right = mid - 1; } } return -1;}int main(){ int arr[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; int key = 0; int sz = sizeof(arr) / sizeof(arr[0]); scanf("%d", &key); int ret = binsearch(key, arr, sz); if (ret == -1) { printf("not exist\n"); } else { printf("%d\n", ret); } system("pause"); return 0;}