【数据结构】关于递归的几个例子

# -*- coding: utf-8 -*-


def factorial(n: int):
    if n == 0:
        return 1
    else:
        return n * factorial(n - 1)


def draw_line(tick_length, tick_label=''):
    line = '-' * tick_length
    if tick_label:
        line += ' ' + tick_label
    print(line)


def draw_interval(center_length):
    if center_length > 0:
        draw_interval(center_length - 1)
        draw_line(center_length)
        draw_interval(center_length - 1)


def draw_ruler(num_inches, major_length):
    draw_line(major_length, '0')
    for j in range(1, 1 + num_inches):
        draw_interval(major_length - 1)
        draw_line(major_length, str(j))


def binary_search(data, target, low, height):
    if low > height:
        return False
    else:
        mid = (low + height) // 2  # 先除后向下取整
        if target == data[mid]:
            return True
        if target < data[mid]:
            return binary_search(data, target, low, mid - 1)
        else:
            return binary_search(data, target, mid + 1, height)


import os


def disk_usage(path):
    total = os.path.getsize(path)
    if os.path.isdir(path):
        for filename in os.listdir(path):
            childpath = os.path.join(path, filename)
            total += disk_usage(childpath)
    print("{0:<7}".format(total), path)
    return total


if __name__ == '__main__':
    # after_sort = quick_sort([1, 3, 0, 34, 32, 2, 13, 3])
    # print(after_sort)

    # 递归1, 阶乘
    # print(factorial(4))
    # 递归2，绘制英式标尺
    # draw_ruler(3, 3)
    # 递归3，二分查找
    # data = [2, 3, 4, 5, 67, 89, 91, 92]
    # print(binary_search(data, 89, 0, len(data) - 1))
    # 递归4，文件磁盘使用情况
    disk_usage("/Users/nidazhong/Downloads")