Problem Statement: Flatten Binary Tree to Linked List LeetCode Solution: Given 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 …
Problem Statement Next Greater Element II LeetCode Solution – Given a circular integer array nums (i.e., the next element of nums[nums.length – 1] is nums[0]), return the next greater number for every element in nums. The next greater number of a number x is the first greater number to its traversing order next in the array, which means you could search …
Problem Statement Group Shifted Strings Leetcode Solution – We can shift a string by shifting each of its letters to its successive letter. For example, “abc” can be shifted to be “bcd”. We can keep shifting the string to form a sequence. For example, we can keep shifting “abc” to form the sequence: “abc” -> “bcd” …
Problem Statement: Camelcase Matching Leetcode Solution says that – Given an array of string “queries” and string “pattern”, return boolean array result where result[i] is true where “queries[i]” matches with “pattern”, false otherwise. A query word “queries[i]” matches with “pattern” if you can insert some lowercase English letters in “pattern” so …
Problem Statement Peak Index in a Mountain Array LeetCode Solution – An array arr a mountain if the following properties hold: arr.length >= 3 There exists some i with 0 < i < arr.length – 1 such that: arr[0] < arr[1] < … < arr[i – 1] < arr[i] arr[i] > arr[i + 1] > … > …
Problem Statement Valid Triangle Number LeetCode Solution – Given an integer array nums, return the number of triplets chosen from the array that can make triangles if we take them as side lengths of a triangle. Input: nums = [2,2,3,4] Output: 3 Explanation: Valid combinations are: 2,3,4 (using the first 2) …
Problem Statement: The Maximum Size Subarray Sum Equals k Leetcode Solution – Given an integer array nums and integer k, return the maximum length of a subarray that sums to k. If there is not one, return 0 instead. Example: Input: nums = [1,-1,5,-2,3], k = 3 Output: 4 Explanation: The …
Problem Statement: H-Index Leetcode solution says that – Given an array of integers “citations” where citations[i] is the number of citations a researcher received for their ith paper, return researcher’s H-Index. If several H-Index values are present, return the maximum among them. Definition of H-Index: A scientist has an index …
Problem Statement: Step-By-Step Directions From a Binary Tree Node to Another LeetCode Solution – You are given the root of a binary tree with n nodes. Each node is uniquely assigned a value from 1 to n. You are also given an integer startValue representing the value of the start node s, and a different integer destValue representing the value of the destination …
Problem Statement Reverse Integer LeetCode Solution says that – Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range [-231, 231 – 1], then return 0. Assume the environment does not allow you to store 64-bit integers (signed or unsigned). Example 1: …