python实现二分搜索binary_search

python实现二分搜索binary_search

条件：给定一个升序列表，返回target值的下标，没有则返回-1

def binary_search(data, target):
    target_index = -1
    start_index = 0
    end_index = len(data) - 1

    while True:
        middle_index = (end_index + start_index) // 2
        middle_value = data[middle_index]
        length = end_index + 1 - start_index
        print(f"middle_index： {middle_index}, middle_value: {middle_value}, length: {length}")
        if target == middle_value:
            target_index = middle_index
            break
        # 在右侧
        elif target > middle_value:
            start_index = middle_index + 1
        # 在左侧
        else:
            end_index = middle_index - 1
        # 终止循环条件 ，当每次对分 对分到最后还没找到
        if not length:
            break
    return target_index


if __name__ == '__main__':
    a = [1, 2, 3, 5, 8, 9, 10, 12, 14, 15, 16]
    t_index = binary_search(a, 2)
    print(t_index)