Assignment-MultiplesOf3And5.html

<h1>Euler Problem 1</h1>

Find the sum of multiples of: 
<input type="number" id="FirstNumber" value=3>
 and 
<input type="number" id="SecondNumber" value=5>
 below 
 <input type="number" id="Below" value=1000>
<input type="button" value="Go" onclick="Go()">
<h1 id="Answer1"></h1>
<h1 id="Answer2"></h1>

<script>
  // If we list all the natural numbers below 10 that are multiples of 3 or 5, we
  // get 3, 5, 6 and 9. The sum of these multiples is 23.  Find the sum of all
  // the multiples of 3 or 5 below 1000.

  var firstNumberTag = document.getElementById("FirstNumber");
  var secondNumberTag = document.getElementById("SecondNumber");
  var belowTag = document.getElementById("Below");
  var answer1Tag = document.getElementById("Answer1");
  var answer2Tag = document.getElementById("Answer2");

  function Go() {
    var first = Number(firstNumberTag.value);
    var second = Number(secondNumberTag.value);
    var below = Number(belowTag.value);

    answer1Tag.innerHTML = MultiplesOf3And5BruteForce(first, second, below);
    answer2Tag.innerHTML = MultiplesOf3And5Elegant(first, second, below);
  }

  function MultiplesOf3And5BruteForce(first, second, below) {
    var sum = 0;
    for (var i = 1; i < below; i++) {
       var foundAMatch = false;

        for (var j = 1; j * first < below; j++) {
            if (j * first === i) {
                foundAMatch = true;
            }
        }

        for (var j = 1; j * second < below; j++) {
            if (j * second === i) {
                foundAMatch = true;
            }
        }

        if (foundAMatch === true) {
            sum = sum + i;
        }
    }

    var answer = "Brute Force Answer: " + sum
    console.log(answer);
    return answer;
  }

  function MultiplesOf3And5Elegant(first, second, below) {
    var sum = 0;
    var n = below;
    
    while (n--) {
      if (n % first === 0 || n % second === 0) {
        sum += n;
      }
    }
    
    var answer = "Elegant Answer: " + sum
    console.log(answer);
    return answer;
  }
</script>