Adding new challenge

README.md

@@ -3,4 +3,5 @@
 
 | Exercise | Code | PDF |
 |----------|------|-----|
-| [Hash Tables: Ransom Note](https://www.hackerrank.com/challenges/ctci-ransom-note/problem) | [Code](challenges/ctci-ransom-note/code.js) | [PDF](ctci-ransom-note/text.pdf) |
+| [Hash Tables: Ransom Note](https://www.hackerrank.com/challenges/ctci-ransom-note/problem) | [Code](challenges/ctci-ransom-note/code.js) | [PDF](challenges/ctci-ransom-note/text.pdf) |
+| [Lucky Numbers](https://www.hackerrank.com/challenges/lucky-numbers/problem) | [Code](challenges/lucky-numbers/code.js) | [PDF](challenges/lucky-numbers/text.pdf) |

challenges/lucky-numbers/code.js

@@ -0,0 +1,44 @@
+function luckyNumbers(a, b) {
+  let totalLuckyNumbers = 0;
+  for (let i = a; i <= b; i++) {
+    const list = numberDigitsToArray(i);
+    const digitsSum = list.length > 1 ? getDigitsSum(list) : list;
+
+    if (!isPrime(digitsSum)) continue;
+
+    const squaresSum = list.length > 1 ? getSquaresSum(list) : list;
+
+    if (!isPrime(squaresSum)) continue;
+
+    totalLuckyNumbers += 1;
+  }
+  return totalLuckyNumbers;
+}
+
+function numberDigitsToArray(num) {
+  return Array.from(num.toString()).map(Number);
+}
+
+function getDigitsSum(digits) {
+  const totalDigits = digits.reduce((accumulator, digit) => accumulator + digit);
+  return totalDigits;
+}
+
+function getSquaresSum(squares) {
+  const totalSquares = squares.reduce((accumulator, digit) => {
+    return accumulator + digit ** 2
+  }, 0);
+  return totalSquares;
+}
+
+function isPrime(num) {
+  const sqrtnum = Math.floor(Math.sqrt(num));
+  let prime = num != 1;
+  for (let i = 2; i < sqrtnum + 1; i++) {
+    if (num % i == 0) {
+      prime = false;
+      break;
+    }
+  }
+  return prime;
+}