基本查找算法

1、二分查找

①递归

int binSort(int* arr, int left, int right, int key) {
    if (left > right) {
        return NULL;
    }

    int mid = (left + right) / 2;
    if (arr[mid] == key) {
        return mid;
    }

    if (key > arr[mid]) {
        binSort(arr, mid + 1, right, key);
    }
    else {
        binSort(arr, left, mid - 1, key);
    }
}

②迭代

int binSort(int* arr, int left, int right, int key) {
    while (left <= right) {//注意是<=，而不是 <
        int mid = left + (right - left) / 2;
        if (arr[mid] == key) {
            return mid;
        }
        if (key > arr[mid]) {
            left = mid + 1;
        }
        else {
            right = mid - 1;
        }
    }
    return NULL;

}

待后续补充