Valid Anagram

Author: charlesbuczel

0242_validAnagram.js

@@ -0,0 +1,32 @@
+/**
+ * @param {string} s First string.
+ * @param {string} t Second string
+ * @return {boolean} Are strings anagrams of each other.
+ * @summary Valid Anagram {@link https://leetcode.com/problems/valid-anagram/solution/}
+ * @description Given two input strings return true if they are anagrams.
+ * Space O(1) - Always two arrays of 26 items.
+ * Time O(n) - Only loop two arrays if both strings are euqal length, hence 2 loops of n.
+ */
+const isAnagram = (s, t) => {
+  if (s.length !== t.length) return false;
+
+  const OFFSET = 'a'.charCodeAt();
+  const ENGLISH_LETTERS_COUNT = 26;
+
+  const countsS = Array(ENGLISH_LETTERS_COUNT);
+  const countsT = Array(ENGLISH_LETTERS_COUNT);
+
+  for (let i = 0; i < s.length; i++) {
+    const index = s[i].charCodeAt() - OFFSET;
+
+    countsS[index] = countsS[index] ? countsS[index] + 1 : 1;
+  }
+
+  for (let i = 0; i < t.length; i++) {
+    const index = t[i].charCodeAt() - OFFSET;
+
+    countsT[index] = countsT[index] ? countsT[index] + 1 : 1;
+  }
+
+  return countsS.every((count, index) => count === countsT[index]);
+};

0438_findAllAnagramsInAString.js

@@ -4,8 +4,8 @@
  * @return {number[]} Array with indexes of all substrings that are anagrams of word.
  * @summary Find All Anagrams in a String {@link https://leetcode.com/problems/find-all-anagrams-in-a-string/}
  * @description Given two input strings return indexes of substrings that are anagrams of second input.
- * Space O(A+B) - A length of string 'word', B length of string 'stream'.
- * Time O(1) - Two new arrays, each of 26 elements.
+ * Space O(1) - Two new arrays, each of 26 elements.
+ * Time O(A+B) - A length of string 'word', B length of string 'stream'.
  */
 const findAnagrams = (stream, word) => {
   const counts = Array(26);