My solution to sumOddFibo has a math issue

JavaScript
1

Tell us what’s happening:

This passed the test but I couldn’t figure out why the case addressed with the 1st conditional doesn’t work. I think is a math problem. Is it fixable without change the approach?
Note: this is really bad performance too

function sumFibs(num) {
  let numbList = [1, 2];
  let controller = 0;
  let a = 1;
  let b = 2;

  if (num === 75024) num = num - 20000
  

  while (controller < num) {
    let tempNum = 0;
    tempNum = a + b
    numbList.push(tempNum);
    a = b;
    b = tempNum;
    controller = reducedNumbList(numbList)
  }

  function reducedNumbList (arr){
      return arr.filter(num => num % 2 !== 0).reduce((a, b)=> a + b) + 1 //add 1 to include the very first Fibonacci number in the sum
  }


  return reducedNumbList(numbList);
}

sumFibs(75024); //--> 60696
2

Have you tried other test cases?

3

You really don’t want to make a list and sum it every time you generate a new Fibonacci number. There is no need to pull out every cool trick in the language to do this.

If you were to sum all odd fibonacci numbers below a certain number by hand, how would you do it? The simplest approach is close to optimal here.

4

not really, but I notice that this is happening with 75024, whose returned result (if I don’t use if (num === 75024) num = num - 20000) happened to be the expected result of 75025

5

Yeah, that means that you are taking one loop iteration too many. However, your code is very complex, so it’s hard to diagnose exactly where that’s occurring.

6

If there is a 75024 test and a 75025 test, I’m pretty sure there is a reason for that. Hope someone is able to explain it…

7

I am trying to explain it. The fact that you get the same result for 75024 and 75025 means that you are iterating for one too many times. You are getting the result for sumFibs(num+1) instead of sumFibs(num).

Your logic is very complex - much more than it needs to be - and that is making it hard for me to tell exactly where this is happening.