Given a linked list, swap every two adjacent nodes and return its head. For example, Given 1->2->3-…

Given a string s1, we may represent it as a binary tree by partitioning it to two non-empty substrings re…

Given a list, rotate the list to the right by k places, where k is non-negative. For examp…

Reverse a linked list from position m to n. Do it in-place and in one-pass. For example: Given&…

Follow up for problem “Populating Next Right Pointers in Each Node“. What if the given tree could …

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together th…

Given a string containing only digits, restore it by returning all possible valid IP address combinations. For…

Given an array of non-negative integers, you are initially positioned at the first index of the array. Each el…

题目： Given an array of integers, find two numbers such that they add up to a specific target number. The functi…

题目： Given a string, find the length of the longest substring without repeating characters. For example, the lo…

Given an array of non-negative integers, you are initially positioned at the first index of the array. Each el…

Given a 2D board containing 'X' and 'O', capture all regions surrounded by 'X'. A region i…