213. House Robber II You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed. All houses at this ...

226. Invert Binary TreeInvert a binary tree.Example:Input: 4 / 2 7 / / 1 3 6 9Output: 4 / 7 2 / / 9 ...

Say you have an array for which the _i_th element is the price of a given stock on day i.

Given a sorted linked list, delete all duplicates such that each element appear only once.

Remove all elements from a linked list of integers that have value val.

82. Remove Duplicates from Sorted List II

Sort a linked list in O(n log n) time using constant space complexity.

Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.

Convert a non-negative integer to its english words representation. Given input is guaranteed to be less than 231 - 1.

Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.