Add solution #652

Author: JoshCrozier

0652-find-duplicate-subtrees.js

@@ -0,0 +1,42 @@
+/**
+ * 652. Find Duplicate Subtrees
+ * https://leetcode.com/problems/find-duplicate-subtrees/
+ * Difficulty: Medium
+ *
+ * Given the root of a binary tree, return all duplicate subtrees.
+ *
+ * For each kind of duplicate subtrees, you only need to return the root node of any one of them.
+ *
+ * Two trees are duplicate if they have the same structure with the same node values.
+ */
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {TreeNode[]}
+ */
+var findDuplicateSubtrees = function(root) {
+  const map = new Map();
+  const result = [];
+
+  serialize(root);
+
+  return result;
+
+  function serialize(node) {
+    if (!node) return '#';
+    const key = `${node.val},${serialize(node.left)},${serialize(node.right)}`;
+    map.set(key, (map.get(key) || 0) + 1);
+    if (map.get(key) === 2) {
+      result.push(node);
+    }
+    return key;
+  }
+};

README.md

@@ -490,6 +490,7 @@
 648|[Replace Words](./0648-replace-words.js)|Medium|
 649|[Dota2 Senate](./0649-dota2-senate.js)|Medium|
 650|[2 Keys Keyboard](./0650-2-keys-keyboard.js)|Medium|
+652|[Find Duplicate Subtrees](./0652-find-duplicate-subtrees.js)|Medium|
 653|[Two Sum IV - Input is a BST](./0653-two-sum-iv-input-is-a-bst.js)|Easy|
 654|[Maximum Binary Tree](./0654-maximum-binary-tree.js)|Medium|
 680|[Valid Palindrome II](./0680-valid-palindrome-ii.js)|Easy|