DescriptionGiven a binary tree, return the zigzag level order traversal of its nodes’ values. (ie, from left to right, then right to left for the next level and alternate between). For example:Given b

DescriptionGiven a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST. The original problem is here. The original code is here.

DescriptionGiven a binary tree, return the postorder traversal of its nodes’ values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [3,2,1]. The original problem is here

DescriptionSort a linked list in O(n log n) time using constant space complexity. The original problem is here. The original code is here.

DescriptionGiven a binary search tree, write a function kthSmallest to find the kth smallest element in it. Note:You may assume k is always valid, 1 ≤ k ≤ BST’s total elements. The original problem is

DescriptionFollow up for “Unique Paths”: Now consider if some obstacles are added to the grids. How many unique paths would there be? An obstacle and empty space is marked as 1 and 0 respectively in t

DescriptionThe original problem is here. The original code is here.

DescriptionGiven a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place. The original problem is here. The original code is here.

DescriptionYou 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? The original problem is here. The original code is

DescriptionGiven an array with n objects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order red, white and blue. Here, we will use the i