Complete telephoneWords.js using recursion

fay-jai · Jan 2, 2015 · 42edbe5 · 42edbe5
1 parent b6f89cf
commit 42edbe5
Showing 1 changed file with 17 additions and 2 deletions.
diff --git a/telephoneWords/telephoneWords.js b/telephoneWords/telephoneWords.js
@@ -41,6 +41,21 @@ var phoneDigitsToLetters = {
 };
 
 
-var telephoneWords = function(digitString) {
-  // TODO: return every combination that can be spelled on a phone with these digits
+var telephoneWords = function (digitString) {
+  var len    = digitString.length;
+  var result = [];
+  var recur;
+
+  if ( len <= 0 ) return [];
+  if ( len === 1 ) return phoneDigitsToLetters[ digitString ].split('');
+
+  recur = telephoneWords( digitString.slice(1) );
+
+  phoneDigitsToLetters[ digitString[0] ].split('').forEach(function (letter) {
+    recur.forEach(function (array) {
+      result.push( Array.prototype.concat( letter, array ) );
+    });
+  });
+
+  return result;
 };