Add solution #273

Author: JoshCrozier

README.md

@@ -44,6 +44,7 @@
 263|[Ugly Number](./0263-ugly-number.js)|Easy|
 264|[Ugly Number II](./0264-ugly-number-ii.js)|Medium|
 268|[Missing Number](./0268-missing-number.js)|Easy|
+273|[Integer to English Words](./0273-integer-to-english-words.js)|Hard|
 283|[Move Zeroes](./0283-move-zeroes.js)|Easy|
 345|[Reverse Vowels of a String](./0345-reverse-vowels-of-a-string.js)|Easy|
 347|[Top K Frequent Elements](./0347-top-k-frequent-elements.js)|Medium|

solutions/0273-integer-to-english-words.js

@@ -0,0 +1,33 @@
+/**
+ * 273. Integer to English Words
+ * https://leetcode.com/problems/integer-to-english-words/
+ * Difficulty: Hard
+ *
+ * Convert a non-negative integer `num` to its English words representation.
+ */
+
+/**
+ * @param {number} num
+ * @return {string}
+ */
+var numberToWords = function(num) {
+  if (num === 0) {
+    return 'Zero';
+  }
+
+  return convert(num).replace(/\s+/g, ' ').trim();
+};
+
+const belowTen = ['', 'One', 'Two', 'Three', 'Four', 'Five', 'Six', 'Seven', 'Eight', 'Nine'];
+const belowTwenty = ['Ten', 'Eleven', 'Twelve', 'Thirteen', 'Fourteen', 'Fifteen', 'Sixteen', 'Seventeen', 'Eighteen', 'Nineteen'];
+const belowHundred = ['', 'Ten', 'Twenty', 'Thirty', 'Forty', 'Fifty', 'Sixty', 'Seventy', 'Eighty', 'Ninety'];
+
+function convert(num) {
+  if (num < 10) return belowTen[num];
+  else if (num < 20) return belowTwenty[num - 10];
+  else if (num < 100) return belowHundred[Math.floor(num / 10)] + ' ' + convert(num % 10);
+  else if (num < 1000) return convert(Math.floor(num / 100)) + ' Hundred ' +  convert(num % 100);
+  else if (num < 1000000) return convert(Math.floor(num / 1000)) + ' Thousand ' +  convert(num % 1000);
+  else if (num < 1000000000) return convert(Math.floor(num / 1000000)) + ' Million ' +  convert(num % 1000000);
+  else return convert(Math.floor(num / 1000000000)) + ' Billion ' +  convert(num % 1000000000);
+}