题目： Determine whether an integer is a palindrome. Do this without extra space. click to show spoilers. Some hi…

Given two words (start and end), and a dictionary, find all shortest transformation sequence(s) from…

Given an unsorted array of integers, find the length of the longest consecutive elements sequence. For example…

Given n non-negative integers representing the histogram’s bar height where the width of each …

Given a linked list, reverse the nodes of a linked list k at a time and return its modified list. If…

Given an array of integers, every element appears twice except for one. Find that single one. Note: …

Given preorder and inorder traversal of a tree, construct the binary tree. Note: You may assume that duplicate…

Given an input string, reverse the string word by word. For example, Given s = “the sky is blue“, …

题目： You are given two linked lists representing two non-negative numbers. The digits are stored in reverse ord…

Given a collection of integers that might contain duplicates, S, return all possible subsets. Note: Eleme…

Given a m x n grid filled with non-negative numbers, find a path from top left to bottom r…

You are climbing a stair case. It takes n steps to reach to the top. Each time you can either climb …