add: 另一个树的子树

README.md

@@ -309,6 +309,11 @@ LeetCode 与 LintCode 解题记录。此为个人练习仓库，代码中对重
   - LeetCode 98. 验证二叉搜索树 https://leetcode-cn.com/problems/validate-binary-search-tree/
   - LintCode 95. 验证二叉查找树 https://www.lintcode.com/problem/validate-binary-search-tree/
 
+- [另一个树的子树](src/tree/subtree-of-another-tree.js)
+
+  - LeetCode 572. 另一个树的子树 https://leetcode-cn.com/problems/subtree-of-another-tree/
+  - LintCode 1165. 另一个树的子树 https://www.lintcode.com/problem/subtree-of-another-tree/description
+
 ## 链表
 
 - [合并K个排序链表](src/list/merge-k-sorted-lists.js)

src/tree/subtree-of-another-tree.js

@@ -0,0 +1,27 @@
+/**
+ * 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} s
+ * @param {TreeNode} t
+ * @return {boolean}
+ */
+export const isSubtree = function (s, t) {
+  if (!s && t) {
+    return false
+  }
+
+  const linkNode = function (node, target) {
+    if ((!node && target) || (node && !target)) return false
+    if (!node && !target) return true
+
+    return node.val === target.val ? linkNode(node.left, target.left) && linkNode(node.right, target.right) : false
+  }
+
+  return linkNode(s, t) || isSubtree(s.left, t) || isSubtree(s.right, t)
+}

test/tree/subtree-of-another-tree.test.js

@@ -0,0 +1,7 @@
+import { isSubtree } from '../../src/tree/subtree-of-another-tree'
+import Tree from './Tree'
+
+test('另一个树的子树', () => {
+  expect(isSubtree(Tree.arrToTree([3, 4, 5, 1, 2]), Tree.arrToTree([4, 1, 2]))).toBe(true)
+  expect(isSubtree(Tree.arrToTree([3, 4, 5, 1, 2, null, null, null, null, 0]), Tree.arrToTree([4, 1, 2]))).toBe(false)
+})