242. 有效的字母异位词

Author: w2xi

README.md

@@ -70,6 +70,7 @@
 |231|[2 的幂](https://leetcode.cn/problems/power-of-two/)|[JavaScript](./algorithms/power-of-two.js)|Easy|
 |234|[回文链表](https://leetcode-cn.com/problems/palindrome-linked-list/)|[JavaScript](./algorithms/palindrome-linked-list.js)|Easy|
 |237|[删除链表中的节点](https://leetcode-cn.com/problems/delete-node-in-a-linked-list/)|[JavaScript](./algorithms/delete-node-in-a-linked-list.js)|Easy|
+|242|[有效的字母异位词](https://leetcode.cn/problems/valid-anagram/)|[JavaScript](./algorithms/valid-anagram.js)|Easy|
 |257|[二叉树的所有路径](https://leetcode.cn/problems/binary-tree-paths/)|[JavaScript](./algorithms/binary-tree-paths.js)|Easy|
 |283|[移动零](https://leetcode.cn/problems/move-zeroes/)|[JavaScript](./algorithms/move-zeroes.js)|Easy|
 |303|[区域和检索 - 数组不可变](https://leetcode.cn/problems/range-sum-query-immutable/)|[JavaScript](./algorithms/range-sum-query-immutable.js)|Easy|

algorithms/valid-anagram.js

@@ -0,0 +1,28 @@
+/**
+ * @param {string} s
+ * @param {string} t
+ * @return {boolean}
+ */
+var isAnagram = function (s, t) {
+  // 数组哈希计数
+  const countArr = Array(26).fill(0);
+
+  if (s.length !== t.length) {
+    return false;
+  }
+
+  for (let char of s) {
+    const index = char.charCodeAt() - "a".charCodeAt();
+    countArr[index]++;
+  }
+
+  for (let char of t) {
+    const index = char.charCodeAt() - "a".charCodeAt();
+    countArr[index]--;
+    if (countArr[index] < 0) {
+      return false;
+    }
+  }
+
+  return true;
+};