Question Given the head of a singly linked list, return true if it is a palindrome or false otherwise. Example 1: Input: head = [1,2,2,1] Output: true Example 2: Input: head = [1,2] Output: false Constraints: The number of nodes in the list is in the range [1, 105]. 0 <= Node.val <= 9 Follow up: Could you do it in O(n) time and O(1) space? Python […]

Question 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. Example 1: Input: n = 1 Output: true Explanation: 20 = 1 Example 2: Input: n = 16 Output: true Explanation: 24 = 16 Example 3: Input: n

Question Given the root of a binary search tree, and an integer k, return the kth smallest value (1-indexed) of all the values of the nodes in the tree. Example 1: Input: root = [3,1,4,null,2], k = 1 Output: 1 Example 2: Input: root = [5,3,6,2,4,null,null,1], k = 3 Output: 3 Constraints: The number of nodes in the tree is n. 1

Question Given an integer array nums and an integer k, return true if there are two distinct indices i and j in the array such that nums[i] == nums[j] and abs(i – j) <= k. Example 1: Input: nums = [1,2,3,1], k = 3 Output: true Example 2: Input: nums = [1,0,1,1], k = 1 Output: true Example 3: Input: nums = [1,2,3,1,2,3], k = 2 Output: false

Question Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct. Example 1: Input: nums = [1,2,3,1] Output: true Example 2: Input: nums = [1,2,3,4] Output: false Example 3: Input: nums = [1,1,1,3,3,4,3,2,4,2] Output: true Constraints: 1 <= nums.length <= 105 -109 <= nums[i] <= 109 Python Solution

Question Given an integer array nums and an integer k, return the kth largest element in the array. Note that it is the kth largest element in the sorted order, not the kth distinct element. You must solve it in O(n) time complexity. Example 1: Input: nums = [3,2,1,5,6,4], k = 2 Output: 5 Example 2: Input: nums = [3,2,3,1,2,4,5,5,6], k = 4 Output: 4 Constraints: 1

Question Given the head of a singly linked list, reverse the list, and return the reversed list. Example 1: Input: head = [1,2,3,4,5] Output: [5,4,3,2,1] Example 2: Input: head = [1,2] Output: [2,1] Example 3: Input: head = [] Output: [] Constraints: The number of nodes in the list is the range [0, 5000]. -5000 <= Node.val <= 5000

Question Given an integer n, return the number of prime numbers that are strictly less than n. Example 1: Input: n = 10 Output: 4 Explanation: There are 4 prime numbers less than 10, they are 2, 3, 5, 7. Example 2: Input: n = 0 Output: 0 Example 3: Input: n = 1 Output: 0 Constraints: 0

Question Write an algorithm to determine if a number n is happy. A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits. Repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does

Question SQL Schema Table: Person +————-+———+ | Column Name | Type | +————-+———+ | id | int | | email | varchar | +————-+———+ id is the primary key column for this table. Each row of this table contains an email. The emails will not contain uppercase letters. Write an SQL query to delete all the duplicate emails,