add js solution for lc problem No. 0273

Author: AE-Hertz

solution/0200-0299/0273.Integer to English Words/Solution.js

@@ -0,0 +1,40 @@
+/**
+ * @param {number} num
+ * @return {string}
+ */
+const lessThanTwenty = [
+  "Zero", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Ten",
+  "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen"
+];
+
+const tens = [
+  "", "", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety"
+];
+
+const thousands = [
+  "", "Thousand", "Million", "Billion"
+];
+
+function numberToWords(num) {
+  if (num === 0) return "Zero";
+
+  let result = "";
+  let i = 0;
+
+  while (num > 0) {
+    if (num % 1000 !== 0) {
+      result = helper(num % 1000) + thousands[i] + " " + result;
+    }
+    num = Math.floor(num / 1000);
+    i++;
+  }
+
+  return result.trim();
+}
+
+function helper(num) {
+  if (num === 0) return "";
+  else if (num < 20) return lessThanTwenty[num] + " ";
+  else if (num < 100) return tens[Math.floor(num / 10)] + " " + helper(num % 10);
+  else return lessThanTwenty[Math.floor(num / 100)] + " Hundred " + helper(num % 100);
+}