Question

我对python还是很陌生，并且我已经受到很多人可能会觉得像小菜一碟的挑战。输出必须是：

The Monkey-child could not fall asleep, so the mother told him a story, he was once a Tiger-child
  The Tiger-child could not fall asleep, so the mother told him a story, he was once a Human-child
    The Human-child could not fall asleep, so the mother told him a story, he was once a Panther-child
      The Panther-child could not fall asleep, so the mother told him a story, he was once a Snake-child
      The Snake-child has tired and fell asleep
     The Panther-child has tired and fell asleep
    The Human-child has tired and fell asleep
   The Tiger-child has tired and fell asleep
  The Monkey-child has tired and fell asleep

下面是要修改的代码（不允许循环for和while）

 import sys

 StorySequence = {
     "Monkey": "Tiger",
     "Tiger": "Human",
     "Panther": "Snake",
     "Snake": "",
     "Human": "Panther"
 }

 def writePaddingForDepth(depth):
     for i in range(0, depth):
         sys.stdout.write('  ')
         sys.stdout.flush()

 def endStory(thread, depth):
     writePaddingForDepth(depth)
     print ("The " + thread + "-child has tired and fell asleep.")
     return True

 def startStory(thread, depth):
    if (len(StorySequence[thread]) == 0):
        return endStory(thread, depth)

 writePaddingForDepth(depth)

 print ("The " + thread + "-child could not fall asleep, "
        "so the mother told him a story, he was once "
        + StorySequence[thread] + "-child")

 ## Code here

 startStory("Monkey", 0)

我试图像使用C语言中的数组那样处理它，但显然，据我所知，它不是dict类型，这对我来说是全新的。在此示例中，我想知道如何在没有for或while循环的情况下实现递归。

Answer 1

代替

for i in range(0, depth):
 sys.stdout.write('  ')

要打印的空格数是depth的两倍，您可以这样做

sys.stdout.write('  ' * depth)

您可以做类似

的操作

def fn(who, depth):
  if(who in StorySequence):
    if(StorySequence[who]!=''):
      print ("\t" * depth + "The " + who + "-child could not fall asleep, "
          "so the mother told him a story, he was once "
          + StorySequence[who] + "-child")
      fn(StorySequence[who], depth+1)
    print ("\t" * depth + "The " + who + "-child has tired and fell asleep.")

fn("Monkey", 0)

递归函数必须具有退出条件，以防止它成为无限递归。

这里，仅在字典中有有效键且值不是空字符串的情况下，才进行递归。

who in StorySequence用于检查字典who中是否存在具有StorySequence内容的键。

没有for或while循环的Dict递归

1 个答案: