Greatest common divisor

[olasunkanmi]

hi guys.

was trying to solve a gcd and scm code challenge but didnt seem to get it.So I saw this code online but dont seem to understand what the gcd and scm functions are doing or even what the a and b parameters are

function smallestCommons(arr) {
      
      var max = Math.max(...arr),
          min = Math.min(...arr),
          range = [],
          scm; // smallestCommonMultiple
      
      for (var i = min; i <= max; i++) {
        range.push(i);
      }
      function gcd(a, b) {  // greatestCommonDivisor based on Euclid's Algorithm
        var answer;    
        for (var x = 0; x <= a; x++) {
          if(a % x === 0 && b % x === 0)
            answer = x;  
        }
        return answer;
      }
      function lcm(a, b) {  // leastCommonMultiple based on Euclid's Algorithm
        return (a * b) / gcd(a, b); 
      }
      scm = range.reduce(lcm);   
      
      return scm; // smallestCommonMultiple
    }
smallestCommons([23, 18]);

[JeremyLT]

Two questions

1. Have you read the Wikipedia articles on GCD and LCM?

2. What kind of math background do you have?

---

Side note: don’t use var

[olasunkanmi]

Yeah, I have read the articles. And my math background isnt all that bad at all. I dont know why wrapping my head around it seem difficult lol

[JeremyLT]

Well, the key first two steps are

1. write a function that finds the GCD of two numbers

2. write a function that finds the LCM of two numbers

So let’s start there. The GCD algorithm presented on Wikipedia is recursive while this one is not. Cn you write the recursive version? Do you understand the algorithm?

[olasunkanmi]

No , I don’t understand the algorithm.

[olasunkanmi]

Okay , I reread the article again and I think I understand it a little more for now,I’d let you know if there’s any more problem. Thanks alot!