尝试使用递归来解决斐波那契(javascript) [英] Trying to Use Recursion to solve Fibonacci (javascript)

问题描述

这是问题:

给出正整数num，返回小于或等于num的所有奇数斐波纳契数的总和.

Given a positive integer num, return the sum of all odd Fibonacci numbers that are less than or equal to num.

斐波那契数列中的前两个数字是1和1.序列中的每个其他数字是前两个数字的总和.斐波那契数列的前六个数字是1、1、2、3、5和8.

The first two numbers in the Fibonacci sequence are 1 and 1. Every additional number in the sequence is the sum of the two previous numbers. The first six numbers of the Fibonacci sequence are 1, 1, 2, 3, 5 and 8.

例如，sumFibs(10)应该返回10，因为所有小于或等于10的斐波那契奇数均为1、1、3和5.

For example, sumFibs(10) should return 10 because all odd Fibonacci numbers less than or equal to 10 are 1, 1, 3, and 5.

这是我尝试过的

function sumFibs(num,  total = [1, 1], n = (total.length - 1 + total.length - 2)) {

if(n == num){
return total;
}

total.push(n);

sumFibs(num, n = (total.length - 1 + total.length - 2), total);

};

问题

是否可以使用我的方法来完成此工作，如果可以，该如何修复语法?如果没有，您将如何解决问题.

Is it possible to use my method to make this work, if so how do I fix the syntax? If not, how would you solve the problem.

非常感谢！

推荐答案

四件事

(1)您不返回递归调用的结果，因此它永远不会传递给调用者:

(1) You don't return the result of the recursive call, therefore it does never get passed up to the caller:

sumFibs(4, [1, 1]) -> sumFibs(4, [1, 1, 2]) -> sumFibs(4, [1, 1, 2, 3])
                                            <- [1, 1, 2, 3]
//                                           v the return you do
//                 v the return you need too

(2)在递归调用中，参数顺序错误.

(2) In the recursive call, the order of arguments is wrong.

(3)我想不是要使用数组长度减去1，而是要访问 total 数组中该位置的属性.

(3) I guess instead of taking the arrays length minus 1, you want to access the property at that position in the total array.

(4)为什么您实际上 n 作为参数?由于它仅取决于 total ，因此也可以只是一个变量:

(4) Why do you actually n as an argument? As it is only depending on total, it could also just be a variable:

function sumFibs(num,  total = [1, 1]) {
  const n = total[total.length - 1] + total[total.length - 2];
  if(n > num){
    return total;
  }

  total.push(n);

  return sumFibs(num, total);
}

console.log(sumFibs(19));

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