James Pan

原题网址：https://leetcode.com/problems/wiggle-sort/Given an unsorted array nums, reorder it in-place such that nums[0] = nums[2] .For example, given nums = [3, 5, 2, 1, 6, 4], one possible ans

原题网址：https://leetcode.com/problems/spiral-matrix-ii/Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.For example,Given n = 3,You should retu

原题网址：https://leetcode.com/problems/validate-binary-search-tree/Given a binary tree, determine if it is a valid binary search tree (BST).Assume a BST is defined as follows:The left subtre

原题网址：https://leetcode.com/problems/symmetric-tree/Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For example, this binary tree is symmetric:

原题网址：https://leetcode.com/problems/binary-tree-level-order-traversal/Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).For

原题网址：https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right

原题网址：https://leetcode.com/problems/binary-tree-postorder-traversal/Given a binary tree, return the postorder traversal of its nodes' values.For example:Given binary tree {1,#,2,3}, 1

原题网址：https://leetcode.com/problems/binary-tree-inorder-traversal/Given a binary tree, return the inorder traversal of its nodes' values.For example:Given binary tree {1,#,2,3}, 1

原题网址：https://leetcode.com/problems/reconstruct-itinerary/Given a list of airline tickets represented by pairs of departure and arrival airports [from, to], reconstruct the itinerary in order.

原题网址：https://leetcode.com/problems/recover-binary-search-tree/Two elements of a binary search tree (BST) are swapped by mistake.Recover the tree without changing its structure.Note:A sol

原题网址：https://leetcode.com/problems/spiral-matrix/Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.For example,Given the following mat

原题网址：https://leetcode.com/problems/rotate-image/You are given an n x n 2D matrix representing an image.Rotate the image by 90 degrees (clockwise).Follow up:Could you do this in-place?

原题网址：https://leetcode.com/problems/zigzag-conversion/The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a

原题网址：https://leetcode.com/problems/zigzag-iterator/Given two 1d vectors, implement an iterator to return their elements alternately.For example, given two 1d vectors:v1 = [1, 2]v2 = [3, 4

原题网址：https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/Given preorder and inorder traversal of a tree, construct the binary tree.Note:You may assume t

原题网址：https://leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal/Given inorder and postorder traversal of a tree, construct the binary tree.Note:You may assume

原题网址：https://leetcode.com/problems/binary-tree-level-order-traversal-ii/Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by le

原题网址：https://leetcode.com/problems/path-sum/Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.

原题网址：https://leetcode.com/problems/flatten-binary-tree-to-linked-list/Given a binary tree, flatten it to a linked list in-place.For example,Given 1 / \ 2 5

原题网址：https://leetcode.com/problems/binary-tree-longest-consecutive-sequence/Given a binary tree, find the length of the longest consecutive sequence path.The path refers to any sequence

原题网址：https://leetcode.com/problems/binary-tree-vertical-order-traversal/Given a binary tree, return the vertical order traversal of its nodes' values. (ie, from top to bottom, column by column).

原题网址：https://leetcode.com/problems/house-robber-iii/The thief has found himself a new place for his thievery again. There is only one entrance to this area, called the "root." Besides the root,

原题网址：https://leetcode.com/problems/verify-preorder-serialization-of-a-binary-tree/One way to serialize a binary tree is to use pre-order traversal. When we encounter a non-null node, we record t