feat(lab): integer to words

Author: amejiarosario

lab/exercises/10-mixed/integer-to-words.js

@@ -32,58 +32,47 @@ const map = {
   90: 'Ninety',
   100: 'Hundred', // One Hundred, Two Hundred
 
-  1_000: 'Thousand', // Four Thousand
-
+  1_000: 'Thousand', // One Thousand
   1_000_000: 'Million', // One Million
-
   1_000_000_000: 'Billion', // One Billion
 };
 
 const keys = [
-  // 1_000_000_000,
-  // 1_000_000,
-  // 1_000,
-  // 100,
-  10,
+  1_000_000_000,
+  1_000_000,
+  1_000,
+  100,
 ];
 
 /**
- * @param {number} num
- * @return {string}
+ * Convert a positive integer into its English representation.
+ *
+ * @param {number} num - The positive integer. Should be <= 2^31 - 1
+ * @return {string} - The English words for the given number
+ *
  * @pomodoro II
  */
 function numberToWords(num) {
-  if (num < 21) return map[num];
+  if (map[num] && num < 99) return map[num];
 
   let ans = [];
-//   let i = 0;
-
-//   while (num && i < keys.length) {
-//     // const div = keys[i++]; // 10
-//     const div = 10;
-//     const reminder = num % div; // 1
-//     const left = num - reminder; // 20
-
-//     if (left && map[left] !== undefined) {
-//       ans.push(map[left]);
-//       num -= left;
-//     }
-
-//     num = reminder;
-//   }
-  ans = ans.concat(numberToWords(Math.floor(num/10) * 10));
-  ans = ans.concat(numberToWords(Math.floor(num % 10)))
+  let i = 0;
+
+  while (num && i < keys.length) {
+    const div = keys[i++];
+    if (Math.floor(num/div)) {
+      ans = ans.concat(numberToWords(Math.floor(num/div)));
+      ans = ans.concat(map[div]);
+      num %= div;
+    }
+  }
+
+  if (num) {
+    ans = ans.concat(numberToWords(Math.floor(num/10) * 10));
+    ans = ans.concat(numberToWords(Math.floor(num % 10)));
+  }
 
   return ans.join(' ');
 };
 
-// convert a number into its English representation
-
-// 21
-// Twenty One
-
-// 1_234_567_891
-
-console.log(process.version);
-
 module.exports = numberToWords;

lab/exercises/10-mixed/integer-to-words.spec-assert.js

@@ -2,11 +2,22 @@
 const assert = require('assert');
 
 const numberToWords = require('./integer-to-words');
+const W9 = 'Nine Hundred Ninety Nine';
 
 assert.equal(numberToWords(0), 'Zero');
 assert.equal(numberToWords(1), 'One');
 assert.equal(numberToWords(20), 'Twenty');
 assert.equal(numberToWords(21), 'Twenty One');
 assert.equal(numberToWords(99), 'Ninety Nine');
+assert.equal(numberToWords(100), 'One Hundred');
+assert.equal(numberToWords(999), W9);
+assert.equal(numberToWords(1_000), 'One Thousand');
+assert.equal(numberToWords(9999), `Nine Thousand ${W9}`);
+assert.equal(numberToWords(1_000_000), 'One Million');
+assert.equal(numberToWords(1_234_567), 'One Million Two Hundred Thirty Four Thousand Five Hundred Sixty Seven');
+assert.equal(numberToWords(999_999_999), `${W9} Million ${W9} Thousand ${W9}`);
+assert.equal(numberToWords(1_234_567_891), `One Billion Two Hundred Thirty Four Million Five Hundred Sixty Seven Thousand Eight Hundred Ninety One`);
+assert.equal(numberToWords(999_999_999_999), `${W9} Billion ${W9} Million ${W9} Thousand ${W9}`);
+assert.equal(numberToWords(2**31 - 1), `Two Billion One Hundred Forty Seven Million Four Hundred Eighty Three Thousand Six Hundred Forty Seven`);
 
 console.log('All tests passed!');