1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
import { TreeNode } from "../binary-tree-inorder-traversal/TreeNode.ts";
function findDuplicateSubtrees(root: TreeNode | null) {    if (!root) return [];    const seen = new Map<string, [node: TreeNode | null, index: number]>();    const repeat = new Set<TreeNode | null>();    let idx = 0;    function dfs(node: TreeNode | null) {        if (!node) {            return 0;        }        const tri = [node.val, dfs(node.left), dfs(node.right)];        const hash = JSON.stringify(tri);        const pair = seen.get(hash);        if (seen.has(hash) && pair) {            repeat.add(pair[0]);            return pair[1];        } else {            seen.set(hash, [node, ++idx]);            return idx;        }    }    dfs(root);    return [...repeat];}export default findDuplicateSubtrees;