# LeetCode Combination Sum III

LeetCode Combination Sum III Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique set of numbers. Example 1: Input: k = 3, n =... Read More

# LeetCode Subtree of Another Tree

LeetCode Subtree of Another Tree Given two non-empty binary trees s and t, check whether tree t has exactly the same structure and node values with a subtree of s. A subtree of s is a tree consists of a node in s and all of this node's descendants. The... Read More

# LeetCode Predict the Winner

LeetCode Predict the Winner Given an array of scores that are non-negative integers. Player 1 picks one of the numbers from either end of the array followed by the player 2 and then player 1 and so on. Each time a player picks a number, that number... Read More

# LeetCode Optimal Division

LeetCode Optimal Division Given a list of positive integers, the adjacent integers will perform the float division. For example, -> 2 / 3 / 4. However, you can add any number of parenthesis at any position to change the priority of operations. You... Read More

# LeetCode Binary Tree Tilt

LeetCode Binary Tree Tilt Given a binary tree, return the tilt of the whole tree. The tilt of a tree node is defined as the absolute difference between the sum of all left subtree node values and the sum of all right subtree node values. Null node has... Read More

# LeetCode Count Complete Tree Nodes

LeetCode Count Complete Tree Nodes Given a complete binary tree, count the number of nodes. Definition of a complete binary tree from Wikipedia: In a complete binary tree every level, except possibly the last, is completely filled, and all nodes in the... Read More

# LeetCode Increasing Subsequences

LeetCode Increasing Subsequences Given an integer array, your task is to find all the different possible increasing subsequences of the given array, and the length of an increasing subsequence should be at least 2 . Example: Input: Output: , , , , ,... Read More

# LeetCode Guess Number Higher or Lower II

LeetCode Guess Number Higher or Lower II We are playing the Guess Game. The game is as follows: I pick a number from 1 to n. You have to guess which number I picked. Every time you guess wrong, I'll tell you whether the number I picked is higher or... Read More

# LeetCode Kth Smallest Element in a BST

LeetCode Kth Smallest Element in a BST Given a binary search tree, write a function kthSmallest to find the kth smallest element in it. Note: You may assume k is always valid, 1 ≤ k ≤ BST's total elements. Follow up: What if the BST is modified... Read More

# LeetCode Most Frequent Subtree Sum

LeetCode Most Frequent Subtree Sum Given the root of a tree, you are asked to find the most frequent subtree sum. The subtree sum of a node is defined as the sum of all the node values formed by the subtree rooted at that node (including the node... Read More