62. Unique Paths
A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below).
The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked 'Finish' in the diagram below).
How many possible unique paths are there?
107. Binary Tree Level Order Traversal II
Given the root of a binary tree, return the inorder traversal of its nodes' values.
82. Remove Duplicates from Sorted List II
Given the head of a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list. Return the linked list sorted as well.
Classic and Basic C/C++ Question
There are four classical question abount C/C++ interview.
235. Lowest Common Ancestor of a Binary Search Tree
Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.
According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes p and q as the lowest node in T that has both p and q as descendants (where we allow a node to be a descendant of itself).”
234. Palindrome Linked List
Given the head of a singly linked list, return true if it is a palindrome.
225. Implement Queue using Stacks
Implement a first in first out (FIFO) queue using only two stacks. The implemented queue should support all the functions of a normal queue (push, peek, pop, and empty).
231. Power of Two
Given an integer n, return true if it is a power of two. Otherwise, return false.
An integer n is a power of two, if there exists an integer x such that n == 2x.
228. Summary Ranges
You are given a sorted unique integer array nums.
Return the smallest sorted list of ranges that cover all the numbers in the array exactly. That is, each element of nums is covered by exactly one of the ranges, and there is no integer x such that x is in one of the ranges but not in nums.
226. Invert Binary Tree
Given the root of a binary tree, invert the tree, and return its root.
Input: root = [4,2,7,1,3,6,9]
Output: [4,7,2,9,6,3,1]