排序map、pq、stack。固定 递归 贪心 开关 二分 滑动窗口（固递贪开二滑）

摘要： Given the root of an n-ary tree, return the preorder traversal of its nodes' values. Nary-Tree input serialization is represented in their level order 阅读全文

摘要： Given a n-ary tree, find its maximum depth. The maximum depth is the number of nodes along the longest path from the root node down to the farthest le 阅读全文

摘要： Given the root of a binary tree, return the preorder traversal of its nodes' values. Example 1: Input: root = [1,null,2,3] Output: [1,2,3] Example 2: 阅读全文

摘要： Given the root of a binary tree, determine if it is a valid binary search tree (BST). A valid BST is defined as follows: The left subtree of a node co 阅读全文

摘要： 基础的三个模板：traverse, dc, bst 【traverse模板】 题：700. Search in a Binary Search Tree 在bst中返回目标所在的最小子树 class Solution { public TreeNode searchBST(TreeNode root 阅读全文

摘要： Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center). For example, this binary tree [1,2,2,3,4,4,3] is symmet 阅读全文

摘要： Given an array where elements are sorted in ascending order, convert it to a height balanced BST. For this problem, a height-balanced binary tree is d 阅读全文

摘要： Given a binary search tree with non-negative values, find the minimum absolute difference between values of any two nodes. Example: Input: 1 \ 3 / 2 O 阅读全文

摘要： tech sells，说话的岗位在费城，用js问了安卓项目, ds web项目api sdk 区别 阅读全文

摘要： ［抄题］： Given two binary trees and imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others 阅读全文