tree

Given a n * n matrix grid of 0’s and 1’s only. We want to represent the grid with a Quad-Tree. Return the root of the Quad-Tree representing the grid. Notice that you can assign the value of a node to True or False when isLeaf is False, and both are accepted in the answer. A Quad-Tree is a tree data structure in which each internal node has exactly four children....

Given the root of a binary tree, return the lowest common ancestor of its deepest leaves. Recall that: The node of a binary tree is a leaf if and only if it has no children The depth of the root of the tree is 0. if the depth of a node is d, the depth of each of its children is d + 1. The lowest common ancestor of a set S of nodes, is the node A with the largest depth such that every node in S is in the subtree with root A....

Given the root of a binary tree, determine if it is a complete binary tree. In a complete binary tree, every level, except possibly the last, is completely filled, and all nodes in the last level are as far left as possible. It can have between 1 and 2h nodes inclusive at the last level h. 1 2 3 4 5 Example 1: Input: root = [1,2,3,4,5,6] Output: true Explanation: Every level before the last is full (ie....

A path in a binary tree is a sequence of nodes where each pair of adjacent nodes in the sequence has an edge connecting them. A node can only appear in the sequence at most once. Note that the path does not need to pass through the root. The path sum of a path is the sum of the node’s values in the path. Given the root of a binary tree, return the maximum path sum of any path....

You have a graph of n nodes labeled from 0 to n - 1. You are given an integer n and a list of edges where edges[i] = [ai, bi] indicates that there is an undirected edge between nodes ai and bi in the graph. Return true if the edges of the given graph make up a valid tree, and false otherwise. 1 2 3 4 Example 1: Input: n = 5, edges = [[0,1],[0,2],[0,3],[1,4]] Output: true 1 2 3 4 Example 2: Input: n = 5, edges = [[0,1],[1,2],[2,3],[1,3],[1,4]] Output: false Constraints:...

Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another computer environment. Design an algorithm to serialize and deserialize a binary tree. There is no restriction on how your serialization/deserialization algorithm should work. You just need to ensure that a binary tree can be serialized to a string and this string can be deserialized to the original tree structure....

Given two nodes of a binary tree p and q, return their lowest common ancestor (LCA). Each node will have a reference to its parent node. The definition for Node is below: 1 2 3 4 5 6 class Node { public int val; public Node left; public Node right; public Node parent; } According to the definition of LCA on Wikipedia: “The lowest common ancestor of two nodes p and q in a tree T is the lowest node that has both p and q as descendants (where we allow a node to be a descendant of itself)....

259. 3Sum Smaller Given an array of n integers nums and an integer target, find the number of index triplets i, j, k with 0 <= i < j < k < n that satisfy the condition nums[i] + nums[j] + nums[k] < target. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Example 1: Input: nums = [-2,0,1,3], target = 2 Output: 2 Explanation: Because there are two triplets which sums are less than 2: [-2,0,1] [-2,0,3] Example 2: Input: nums = [], target = 0 Output: 0 Example 3: Input: nums = [0], target = 0 Output: 0 Constraints:...

315. Count of Smaller Numbers After Self You are given an integer array nums and you have to return a new counts array. The counts array has the property where counts[i] is the number of smaller elements to the right of nums[i]. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Example 1: Input: nums = [5,2,6,1] Output: [2,1,1,0] Explanation: To the right of 5 there are 2 smaller elements (2 and 1)....

255. Verify Preorder Sequence in Binary Search Tree Given an array of unique integers preorder, return true if it is the correct preorder traversal sequence of a binary search tree. 1 2 3 4 5 6 7 8 9 Example 1: Input: preorder = [5,2,1,3,6] Output: true Example 2: Input: preorder = [5,2,6,1,3] Output: false Constraints: 1 <= preorder.length <= 10^4 1 <= preorder[i] <= 10^4 All the elements of preorder are unique....

654. Maximum Binary Tree You are given an integer array nums with no duplicates. A maximum binary tree can be built recursively from nums using the following algorithm: Create a root node whose value is the maximum value in nums. Recursively build the left subtree on the subarray prefix to the left of the maximum value. Recursively build the right subtree on the subarray suffix to the right of the maximum value....

307. Range Sum Query - Mutable Given an integer array nums, handle multiple queries of the following types: Update the value of an element in nums. Calculate the sum of the elements of nums between indices left and right inclusive where left <= right. Implement the NumArray class: NumArray(int[] nums) Initializes the object with the integer array nums. void update(int index, int val) Updates the value of nums[index] to be val....

270. Closest Binary Search Tree Value Given the root of a binary search tree and a target value, return the value in the BST that is closest to the target. 1 2 3 4 Example 1: Input: root = [4,2,5,1,3], target = 3.714286 Output: 4 1 2 3 4 Example 2: Input: root = [1], target = 4.428571 Output: 1 Constraints: The number of nodes in the tree is in the range [1, 104]....

515. Find Largest Value in Each Tree Row Given the root of a binary tree, return an array of the largest value in each row of the tree (0-indexed). 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Example 1: Input: root = [1,3,2,5,3,null,9] Output: [1,3,9] Example 2: Input: root = [1,2,3] Output: [1,3] Example 3: Input: root = [1] Output: [1] Example 4: Input: root = [1,null,2] Output: [1,2] Example 5: Input: root = [] Output: [] Constraints:...

938. Range Sum of BST Given the root node of a binary search tree and two integers low and high, return the sum of values of all nodes with a value in the inclusive range [low, high]. 1 2 3 4 5 Example 1: Input: root = [10,5,15,3,7,null,18], low = 7, high = 15 Output: 32 Explanation: Nodes 7, 10, and 15 are in the range [7, 15]. 7 + 10 + 15 = 32....