Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity. ExampleInput:[ 1->4->5, 1->3->4, 2-& ...

Given a linked list, swap every two adjacent nodes and return its head. You may not modify the values in the list, only nodes itself can be changed. E ...

You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contai ...

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists. ExampleI ...

Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward. ExampleNo.1Input: 121 Output: tru ...

Given a non-negative integer represented as a non-empty array of digits, plus one to the integer. The digits are stored such that the most significant ...

Given a 32-bit signed integer, reverse digits of an integer. ExampleNo.1Input: 123 Output: 321 No.2Input: -123 Output: -321 No.3Input: 120 Output: 21 ...

Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000. ExampleNo.1Input: “babad” Output: ...

Given a string, find the length of the longest substring without repeating characters. ExampleNo.1Input: “abcabcbb” Output: 3 Explanation: The answer ...

Validate if a given string is numeric. Example“0” => true“ 0.1 “ => true“abc” => false“1 a” => false“2e10” => true“ -90e3 “ => tru ...