偶数Fibonacci数的总和 [英] Sum of Even Fibonacci numbers

问题描述

我接受了来自 www.hackerrank.com 的挑战，计算了甚至斐波纳契数的总和。我已经提交了计算甚至Fibonacci数的逻辑，但我已经使用循环来计算总和。有没有任何数学逻辑可以计算偶数斐波那契数的总和而不需要循环。在此先感谢。

I got a challenge from www.hackerrank.com, calculate the sum of even Fibonacci number. I have submitted the logic that will calculate even Fibonacci numbers but i have used the loop to calculate the sum. Is there any mathematical logic that will calculate sum of even Fibonacci number without looping. Thanks in advance.

推荐答案

没有。

嗯，这不是真的，你可以把它变成一个递归算法，但......效率更低。



斐波那契数字是一个序列 - 每个术语取决于前两个术语的两个值。因此，为了评估F（n），你需要知道F（n-1）和F（n-2），两者都取决于两个早期的术语。



所以不，你不能在没有涉及循环的情况下神奇地找到F（n）的值。除非您使用该循环预先生成所有值并存储它们供您的应用程序访问 - 但由于序列是无限制的，您不会有空间...：笑：

No.
Well, that's not true, you could make it a recursive algorithm instead, but...that's even less efficient.

Fibonacci numbers are a sequence - each term depends on the two value of the two previous terms. So in order to evaluate F(n), you need to know both F(n-1) and F(n-2), both of which depend on two earlier terms.

So no, you can't magically find the value of F(n) without a loop being involved. Unless you use that loop to generate all the values in advance and store them for your app to access - but since the sequence is unbounded, you don;t have space for that...:laugh:

由于 Fibonacci 系列很容易通过循环生成，如果有其他算法（ simplex sigillum veri ），我甚至都不会打扰。但是你可以试试递归。遗憾的是C＃编程语言不支持尾递归优化 ...哎呀，等等...... C＃中的尾递归 [ ^ ]。

Since the Fibonacci series is easily generated with a loop, I wouldn't even bother if there are alternate algorithms (simplex sigillum veri). However you might try recursion. It is a pity the C# programming language doesn't support tail recursion optimization...Oops, wait... "Tail recursion in C#"[^].

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