递归函数 [英] Recursive Functions

问题描述

我正在尝试写一个Power（x，n）的递归版本，它的工作原理是

将n分成两半（n = n / 2的一半），平方

Power（x，n / 2），如果n为奇数，则再次乘以x，并找到一个

合适的基本情况来停止递归。有人可以给我一个

的例子吗？


谢谢！

解决方案

< blockquote> On Mon，27 Oct 2003 09:54:05 -0800，dmattis写道：

我正在尝试编写一个递归版本的Power（x，n），它的工作原理是<将n分成两半（其中n = n / 2的一半），平方
Power（x，n / 2），如果n为奇数则再次乘以x，并找到
合适的基础案例来阻止递归。有人可以给我一个
这样的例子吗？

这个问题不在这里。我建议你尝试在comp.programming中发布
，但我实际上无法弄明白你想要什么。你已经完全描述了算法，

你还想要什么？


-Sheldon


p.s.我希望你想要的东西不是为了某人简单地为你做功课。

在2003-10-27，dmattis< dm ***** @ yahoo.com>写道：

我正在尝试写一个递归版本的Power（x，n），它的工作原理是将n分成两半（n = n / 2的一半），平方<如果n是奇数，则功率（x，n / 2）再次乘以x，并找到一个合适的基本情况来停止递归。有人可以给我一个这样的例子吗？

这不是C问题......但C答案是使用pow（）（除非你

是故意避免浮点数，在这种情况下表格查询

是有序的。）


< DYOHW>将您的单词问题重写为重复关系。使用

归纳来证明这种重复正确计算x到第n个
的功率。在这一点上应该很明显你的功能应该是什么样的b $ b看起来像你的基本情况。 < / DYOHW>


- James

dmattis写道：

我正在尝试写一个递归版本的Power（x，n），通过将n分解成两半（n = n / 2的一半），平方
Power（x，n / 2）如果n是奇数，则再次乘以x，并找到一个合适的基本情况来停止递归。有人可以给我一个这样的例子吗？

这似乎是一个相当清楚的程序描述，

假设`n ''是一个非负整数。 （如果'n''可以是

否定问题就更难了;如果'n''可以是非整数

问题要困难得多。）问题是什么你有

吗？也许如果你向我们展示你到目前为止写的东西，

有人可以提供帮助。


-
Er*********@sun.com

I am trying to write a recursive version of Power(x,n) that works by
breaking n down into halves(where half of n=n/2), squaring
Power(x,n/2), and multiplying by x again if n was odd, and to find a
suitable base case to stop the recursion. Can someone give me an
example of this?

Thanks!

解决方案

On Mon, 27 Oct 2003 09:54:05 -0800, dmattis wrote:

I am trying to write a recursive version of Power(x,n) that works by
breaking n down into halves(where half of n=n/2), squaring
Power(x,n/2), and multiplying by x again if n was odd, and to find a
suitable base case to stop the recursion. Can someone give me an
example of this?

This question is off topic here. I would suggest you try
posting in comp.programming, but I can''t actually figure out
what you want. You''ve described the algorithm completely,
what more do you want?

-Sheldon

p.s. I''m hoping that what you want isn''t for someone to simply
do your homework for you.

On 2003-10-27, dmattis <dm*****@yahoo.com> wrote:

I am trying to write a recursive version of Power(x,n) that works by
breaking n down into halves(where half of n=n/2), squaring
Power(x,n/2), and multiplying by x again if n was odd, and to find a
suitable base case to stop the recursion. Can someone give me an
example of this?

This is not a C question... but the C answer is use pow() (unless you
are purposefully avoiding floating point, in which case a table lookup
is in order).

<DYOHW> Rewrite your word problem into a recurrence relationship. Use
induction to prove this recurrence correctly calculates x to the nth
power. It should be obvious at that point what your function should
look like and what your base case is. </DYOHW>

-- James

dmattis wrote:

I am trying to write a recursive version of Power(x,n) that works by
breaking n down into halves(where half of n=n/2), squaring
Power(x,n/2), and multiplying by x again if n was odd, and to find a
suitable base case to stop the recursion. Can someone give me an
example of this?

This seems a fairly clear description of the procedure,
assuming `n'' is a non-negative integer. (If `n'' can be
negative the problem is harder; if `n'' can be a non-integer
problem is much harder.) What problem are you having with
it? Perhaps if you''d show us what you''ve written thus far,
someone will be able to help.

--
Er*********@sun.com

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