1.2 check perm added HashTable solution

chapter01/1.2 - Check Perm/checkPermute.js

@@ -1,3 +1,5 @@
+// Time O(n log n) for Sorting
+// Space O(n) for sorting
 var checkPermute = function(stringOne, stringTwo) {
   // if different lengths, return false
   if (stringOne.length !== stringTwo.length) {
@@ -11,9 +13,48 @@ var checkPermute = function(stringOne, stringTwo) {
   }
 };
 
+/**
+* @param: {string} str1
+* @param: {string} str2
+* @return: {boolean}
+
+Time O(n) & Space O(n)
+
+Iterate over the initial input string
+Throw all of the elements into a frequency counter
+Iterate over the second input string
+
+Then subtract 1 from each element
+Iterate over the hashTable and make sure all of the values are zero
+
+**/
+
+const checkPermute = function(str1, str2) {
+  const freq = str1.split('').reduce((a,c) => {
+    a[c] = (a[c] || 0 ) + 1
+    return a
+  }, {})
+
+  for (let chr of str2) {
+    freq[chr]--
+  }
+
+  for (let key in freq) {
+    if (freq[key] !== 0) {
+      return false
+    }
+  }
+
+  return true  
+}
+
 // Tests
 console.log(checkPermute('aba', 'aab'), true);
-
 console.log(checkPermute('aba', 'aaba'), false);
+console.log(checkPermute('aba', 'aa'), false);
 
-console.log(checkPermute('aba', 'aa'), false);
+console.log(checkPermute('', ''), true)
+console.log(checkPermute('abc', 'cba'), true)
+console.log(checkPermute('', 'abc'), false)
+console.log(checkPermute('aaaaaaaaaaaaaaaaaa', 'aaaaaaaaaaaaaaaaaa'), true)
+console.log(checkPermute('aaaaaaa1aaaaaaaaaa', 'aaaaaaaaaaaaaaaaaa'), false)