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Flatten Binary Tree to Linked ListGiven the root of a binary tree, flatten the tree into a "linked list":The "linked list" should use the same TreeNode class where the right child pointer points to the next node in the list and the left child pointer is always null.The "linked list" should be in the same order as a pre-order traversal of the binary tree. Example 1:Input: root = [1,2,5,3,4,null,6..

Roman to IntegerRoman numerals are represented by seven different symbols: I, V, X, L, C, D and M.Symbol ValueI 1V 5X 10L 50C 100D 500M 1000For example, 2 is written as II in Roman numeral, just two ones added together. 12 is written as XII, which is simply X + II. The number 27 is written as XXVII, which i..

Product of Array Except SelfGiven an integer array nums, return an array answer such that answer[i] is equal to the product of all the elements of nums except nums[i].The product of any prefix or suffix of nums is guaranteed to fit in a 32-bit integer.You must write an algorithm that runs in O(n) time and without using the division operation. Example 1:Input: nums = [1,2,3,4]Output: [24,12,8,6]E..

Find Peak ElementA peak element is an element that is strictly greater than its neighbors.Given a 0-indexed integer array nums, find a peak element, and return its index. If the array contains multiple peaks, return the index to any of the peaks.You may imagine that nums[-1] = nums[n] = -∞. In other words, an element is always considered to be strictly greater than a neighbor that is outside the..

Reverse BitsReverse bits of a given 32 bits unsigned integer.Note:Note that in some languages, such as Java, there is no unsigned integer type. In this case, both input and output will be given as a signed integer type. They should not affect your implementation, as the integer's internal binary representation is the same, whether it is signed or unsigned.In Java, the compiler represents the sig..

Factorial Trailing ZeroesGiven an integer n, return the number of trailing zeroes in n!.Note that n! = n * (n - 1) * (n - 2) * ... * 3 * 2 * 1. Example 1:Input: n = 3Output: 0Explanation: 3! = 6, no trailing zero.Example 2:Input: n = 5Output: 1Explanation: 5! = 120, one trailing zero.Example 3:Input: n = 0Output: 0 Constraints:0 4 Follow up: Could you write a solution that works in logarithmic t..

Plus OneYou are given a large integer represented as an integer array digits, where each digits[i] is the ith digit of the integer. The digits are ordered from most significant to least significant in left-to-right order. The large integer does not contain any leading 0's.Increment the large integer by one and return the resulting array of digits. Example 1:Input: digits = [1,2,3]Output: [1,2,4]..

Best Time to Buy and Sell Stock IIYou are given an integer array prices where prices[i] is the price of a given stock on the ith day.On each day, you may decide to buy and/or sell the stock. You can only hold at most one share of the stock at any time. However, you can buy it then immediately sell it on the same day.Find and return the maximum profit you can achieve. Example 1:Input: prices = [7..

Best Time to Buy and Sell Stock IIIYou are given an array prices where prices[i] is the price of a given stock on the ith day.Find the maximum profit you can achieve. You may complete at most two transactions.Note: You may not engage in multiple transactions simultaneously (i.e., you must sell the stock before you buy again). Example 1:Input: prices = [3,3,5,0,0,3,1,4]Output: 6Explanation: Buy o..

Add Two NumbersYou are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order, and each of their nodes contains a single digit. Add the two numbers and return the sum as a linked list.You may assume the two numbers do not contain any leading zero, except the number 0 itself. Example 1:Input: l1 = [2,4,3], l2 = [5,6,4]Output: [7,0,8]Explana..