def binarySearchDemo(arr, key):
    """
    python二分查找非递归方式
    :param arr:待排序列，有序集合
    :param key:带查找元素
    """
    low = 0
    high = len(arr) - 1

    while low <= high:
        mid = (low + high) // 2

        if key > arr[mid]:
            low = mid + 1
        elif key < arr[mid]:
            high = mid - 1
        else:
            return mid
    return -1


def binarySearchDemo2(arr, start, end, key):
    """
    python二分查找递归方式
    :param arr:待排序列，有序集合
    :param start:待排序列,开始位置
    :param end:待排序列,结束位置
    :param key:带查找元素
    """
    if start > end:
        return -1

    mid = (start + end) // 2

    if key > arr[mid]:
        return binarySearchDemo2(arr, mid + 1, end, key)
    elif key < arr[mid]:
        return binarySearchDemo2(arr, start, mid - 1, key)
    else:
        return mid


nums = [6, 12, 33, 87, 90, 97, 108, 561]

# 非递归实现
print(binarySearchDemo(nums, 90))

# 递归实现
print(binarySearchDemo2(nums, 0, len(nums) - 1, 90))