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Given a positive integer num, write a function which returns True if num is a perfect square else False.Note: Do not use any built-in library function such as sqrt.Example 1:Input: 16Output: trueExample 2:Input: 14Output: false题意判断指定的数是否是平方数

题目链接 1232. Check If It Is a Straight Line | 1232. 缀点成线You are given an array coordinates, coordinates[i] = [x, y], where [x, y] represents the coordinate of a point. Check if these points make a s...

题目链接 383. Ransom Note |Given an arbitrary ransom note string and another string containing letters from all the magazines, write a function that will return true if the ransom note can be constru...

题目链接 771. Jewels and Stones |You’re given strings J representing the types of stones that are jewels, and S representing the stones you have. Each character in S is a type of stone you have. You ...

题目链接 278.First Bad Version |You are a product manager and currently leading a team to develop a new product. Unfortunately, the latest version of your product fails the quality check. Since each ...

Given an n-ary tree, return the preorder traversal of its nodes’ values.Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null va...

Given a binary tree, find its maximum depth.The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.Note: A leaf is a node with no children....

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.Note: A leaf is a node with no children.Example:G...

You are given a perfect binary tree where all leaves are on the same level, and every parent has two children. The binary tree has the following definition:struct Node { int val; Node *left; No...

Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes p a...

Given a binary treestruct Node { int val; Node *left; Node *right; Node *next;}Populate each next pointer to point to its next right node. If there is no next right node, the next pointer ...

Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between t...

Find the sum of all left leaves in a given binary tree.Example: 3 / \ 9 20 / \ 15 7There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24....

Given a binary tree, find its minimum depth.The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.Note: A leaf is a node with no children....

题目链接 LeetCode | 力扣Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For example, this binary tree [1,2,2,3,4,4,3] is symmetric: 1 / \ 2 2 / ...

题目链接 LeetCode | 力扣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...

You are given a binary tree in which each node contains an integer value.Find the number of paths that sum to a given value.The path does not need to start or end at the root or a leaf, but it must ...

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.Note: A leaf is a node with no children.Example:G...

题目链接 LeetCode | [力扣]Invert a binary tree.Example:Input: 4 / \ 2 7 / \ / \1 3 6 9Output: 4 / \ 7 2 / \ / \9 6 3 1Trivia:This problem was inspir...

Given a binary tree, you need to compute the length of the diameter of the tree. The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This path may or may n...

Given a binary tree, find its maximum depth.The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.Note: A leaf is a node with no children....

Given a binary tree, determine if it is height-balanced.For this problem, a height-balanced binary tree is defined as:a binary tree in which the left and right subtrees of every node differ in heig...

Given an array where elements are sorted in ascending order, convert it to a height balanced BST.For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the ...

Design a class to find the kth largest element in a stream. Note that it is the kth largest element in the sorted order, not the kth distinct element.Your KthLargest class will have a constructor whi...

Given the root node of a binary search tree (BST) and a value to be inserted into the tree, insert the value into the BST. Return the root node of the BST after the insertion. It is guaranteed that th...

Given the root node of a binary search tree (BST) and a value. You need to find the node in the BST that the node’s value equals the given value. Return the subtree rooted with that node. If such node...

Implement an iterator over a binary search tree (BST). Your iterator will be initialized with the root node of a BST.Calling next() will return the next smallest number in the BST.Example:BSTIterat...

Given a binary tree, determine if it is a valid binary search tree (BST).Assume a BST is defined as follows:The left subtree of a node contains only nodes with keys less than the node’s key.The ri...

Given a string s, find the longest palindromic subsequence’s length in s. You may assume that the maximum length of s is 1000.Example 1:Input:"bbbab"Output:4One possible longest palindromic su...

Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum.Example:Input: [-2,1,-3,4,-1,2,1,-5,4],Output: 6Explanatio...

Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers on the row below.For example, given the following triangle[ [2], [3,4], [6,5,7]...

Given an unsorted array of integers, find the length of longest increasing subsequence.Example:Input: [10,9,2,5,3,7,101,18]Output: 4 Explanation: The longest increasing subsequence is [2,3,7,101],...

Given a binary tree, determine if it is a valid binary search tree (BST).Assume a BST is defined as follows:The left subtree of a node contains only nodes with keys less than the node’s key.The ri...

Given an n-ary tree, return the level order traversal of its nodes’ values.Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null...

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For example, this binary tree [1,2,2,3,4,4,3] is symmetric: 1 / \ 2 2 / \ / \3 4 4 3But ...

二叉树是一棵以根节点开始，每个节点含有不超过2个子节点的树。 让我们将这个定义扩展到N叉树。 一棵以根节点开始，每个节点不超过N个子节点的树，称为N叉树。前缀树，又称字典树( Trie)， 就是一个常用的 N 叉树。遍历LeetCode589.N-ary Tree Preorder TraversalEasy590.N-ary Tree Postorder T...

Given an n-ary tree, return the postorder traversal of its nodes’ values.Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null v...

Given a n-ary tree, find its maximum depth.The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.Nary-Tree input serialization is represen...

Return the root node of a binary search tree that matches the given preorder traversal.(Recall that a binary search tree is a binary tree where for every node, any descendant of node.left has a value...

Given inorder and postorder traversal of a tree, construct the binary tree.Note:You may assume that duplicates do not exist in the tree.For example, giveninorder = [9,3,15,20,7]postorder = [9,15,...