Question Given an array nums of integers, return the length of the longest arithmetic subsequence in nums. Recall that a subsequence of an array nums is a list nums[i1], nums[i2], …, nums[ik] with 0 <= i1 < i2 < … < ik <= nums.length – 1, and that a sequence seq is arithmetic if seq[i+1] – seq[i] are all the same value (for 0 <= i < seq.length – 1). Example 1: Input: nums = [3,6,9,12] Output: […]

Question You are given the root of a binary tree where each node has a value 0 or 1. Each root-to-leaf path represents a binary number starting with the most significant bit. For example, if the path is 0 -> 1 -> 1 -> 0 -> 1, then this could represent 01101 in binary, which is 13. For all leaves in the tree, consider

Question A valid parentheses string is either empty “”, “(” + A + “)”, or A + B, where A and B are valid parentheses strings, and + represents string concatenation. For example, “”, “()”, “(())()”, and “(()(()))” are all valid parentheses strings. A valid parentheses string s is primitive if it is nonempty, and there does not exist a way to split it into s = A + B, with A and B nonempty valid

Question Given an array of integers preorder, which represents the preorder traversal of a BST (i.e., binary search tree), construct the tree and return its root. It is guaranteed that there is always possible to find a binary search tree with the given requirements for the given test cases. A binary search tree is a binary tree where for every node, any descendant

Question Given a string array words, return an array of all characters that show up in all strings within the words (including duplicates). You may return the answer in any order. Example 1: Input: words = [“bella”,”label”,”roller”] Output: [“e”,”l”,”l”] Example 2: Input: words = [“cool”,”lock”,”cook”] Output: [“c”,”o”] Constraints: 1 <= words.length <= 100 1 <= words[i].length <= 100 words[i] consists of

Question In a town, there are n people labeled from 1 to n. There is a rumor that one of these people is secretly the town judge. If the town judge exists, then: The town judge trusts nobody. Everybody (except for the town judge) trusts the town judge. There is exactly one person that satisfies properties 1 and 2. You are given an

Question Given the root of a binary tree with unique values and the values of two different nodes of the tree x and y, return true if the nodes corresponding to the values x and y in the tree are cousins, or false otherwise. Two nodes of a binary tree are cousins if they have the same depth with different parents. Note that in a binary tree, the root node is

Question Given an integer array nums sorted in non-decreasing order, return an array of the squares of each number sorted in non-decreasing order. Example 1: Input: nums = [-4,-1,0,3,10] Output: [0,1,9,16,100] Explanation: After squaring, the array becomes [16,1,0,9,100]. After sorting, it becomes [0,1,9,16,100]. Example 2: Input: nums = [-7,-3,2,3,11] Output: [4,9,9,49,121] Constraints: 1 <= nums.length <= 104 -104 <= nums[i] <= 104 nums is sorted

Question A binary tree is uni-valued if every node in the tree has the same value. Given the root of a binary tree, return true if the given tree is uni-valued, or false otherwise. Example 1: Input: root = [1,1,1,1,1,null,1] Output: true Example 2: Input: root = [2,2,2,5,2] Output: false Constraints: The number of nodes in the tree is in the range [1, 100]. 0

Question You are given an integer array nums with the following properties: nums.length == 2 * n. nums contains n + 1 unique elements. Exactly one element of nums is repeated n times. Return the element that is repeated n times. Example 1: Input: nums = [1,2,3,3] Output: 3 Example 2: Input: nums = [2,1,2,5,3,2] Output: 2 Example 3: Input: nums = [5,1,5,2,5,3,5,4] Output: 5 Constraints: 2 <=