added answer for ch1_q4

Author: Phil Targun

lib/data-structures/chapter-1/1_4.js

@@ -0,0 +1,25 @@
+module.exports = Strings1_4 = (function() {
+  return{
+    // Checks if a string is a permutation of a palindrome
+    // Solution #4 from the book. Assumes ascii character set
+    // @param {String} str - Word or phrase
+    // @retuns {Boolean} - true if a permutation of palindrome exists, false if it does not
+    palindromePermutation: function(str){
+      var distinct = 0;
+      var s_array  = Array.apply(null, Array(256)).map(Number.prototype.valueOf, 0);
+      str = str.toLowerCase();
+      for(var i = 0; i < str.length; i++){
+        if(str[i] == ' '){
+          continue;
+        }
+        s_array[str[i].charCodeAt(0)]++;
+        if(s_array[str[i].charCodeAt(0)] % 2){
+          distinct++;
+        }else{
+          distinct--;
+        }
+      }
+      return (distinct < 2);
+    }
+  }
+}());

test/data-structures/chapter-1/1_4_Spec.js

@@ -0,0 +1,13 @@
+require('../../test_helper');
+describe('1.4 #palindromePermutation', function () {
+  it('returns true if a string is a permutation of a palindrom', function () {
+    expect(Strings1_4.palindromePermutation('Tact Coa')).to.be.true;
+    expect(Strings1_4.palindromePermutation('jhsabckuj ahjsbckj')).to.be.true;
+    expect(Strings1_4.palindromePermutation('Able was I ere I saw Elba')).to.be.true;
+  });
+  it('returns false if a string is not a permutation of a palindrome', function () {
+    expect(Strings1_4.palindromePermutation('So patient a nurse to nurse a patient so')).to.be.false;
+    expect(Strings1_4.palindromePermutation('Random Words')).to.be.false;
+    expect(Strings1_4.palindromePermutation('Not a Palindrome')).to.be.false;
+  });
+});