First solutions found in ES6

Author: Gonzalo Diaz

problem0001.js

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+/**
+ * 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.
+ */
+
+let total = 0;
+let top = 1000;
+
+for (let i= 0; i < top; i++)
+{
+    if(i % 3 == 0 || i % 5 ==0)
+    {
+        console.log(`i = ${i}`);
+        total = total+i;
+    }
+}
+
+console.log(`TOTAL = ${total}`);

problem0002.js

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+// Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:
+
+// 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
+
+// By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.
+
+let i = 0;
+let fibo = 0;
+let last1 = 1;
+let last2 = 0;
+let evenSum = 0;
+do {
+
+        // last2 + last1 = fibo
+        fibo = last2 + last1;
+        console.log(`${i}: ${last2} + ${last1} = ${fibo}`)
+
+        if(fibo % 2 === 0)
+        {
+            evenSum = evenSum + fibo;
+        }
+
+        // next keys:
+        last2 = last1;
+        last1 = fibo;
+    
+    i++;
+} while ( fibo < 4000000 )
+
+console.log(`RESULT = ${evenSum}`)

problem0003.js

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+// problem0003.js
+
+// The prime factors of 13195 are 5, 7, 13 and 29.
+
+// What is the largest prime factor of the number 600851475143 ?
+
+
+//////
+
+// divisors calculated = 71,839,1471,6857,59569,104441,486847,1234169,5753023,10086647,87625999,408464633,716151937,8462696833
+
+//////
+
+let target = 600851475143
+let top = target
+let i;
+
+let n = 100;
+
+// 1 => 10 / 1 => 10
+// 2 => 10 / 2 => 5
+// 3 => 10 / 3 => X
+// 3 => 10 / 4 => X
+
+let divs = [];
+
+// fast divisors finding loop
+for (i=1; i < top; i++)
+{
+    if(target % i === 0 && i != 1 && i != target) {
+
+        divs.push(i);
+        divs.push(target / i)
+
+        top = target / i;
+        console.log(`adding ${i}`)
+    }
+}
+
+// sort divisors
+divs.sort((a, b) => a - b);
+// print all divisors
+console.log(`All divisors of ${target}: ${divs}`)
+
+// Prime checker
+function isPrime(n) {
+    for(let i=2; i < n; i++) {
+        if (n % i == 0) {
+            return false;
+        }
+    }
+    
+    return true;
+} 
+
+let middle;
+if (divs.length % 2 === 0)
+{
+    middle = (divs.length/2) -1;
+} else {
+    middle = (divs.length) - 1;    
+}
+
+// check half divisors, each is Prime? wich is largest?
+let maxPrimeFactor;
+
+i = middle;
+do
+{
+    let prime = isPrime(divs[i]);
+
+    console.log(`${divs[i]} is Prime? ${prime}`)
+
+    if(prime)
+        maxPrimeFactor = divs[i];
+    i--
+} while(i >= 0 && !maxPrimeFactor)
+
+console.log(`${maxPrimeFactor}`)