1. /*
    2.     折半查找的递归实现
    4. */
    5. #include <stdio.h>
    6. #include<stdlib.h>
    7. int halfSearch(int *arr, int num, int low, int mid, int high) {
    8.     if (low > high)return -1;
    9.     if (num == arr[mid]) {//找到，返回位置
    10.         return mid;
    11.     }
    12.     else if (num > arr[mid]) {
    13.         return halfSearch(arr, num, mid + 1, (mid + 1 + high) / 2, high);
    14.     }
    15.     else {
    16.         return halfSearch(arr, num, low, (low + mid - 1) / 2, mid - 1);
    17.     }
    18. }
    21. int main() {
    22.     int arr[] = { 0,1,3, 5,9,12,24,25,35,44,54,55 };
    23.     printf("%d ", halfSearch(arr, 100, 1, 6, 11));
    24.     return 0;
    25. }