951. Flip Equivalent Binary Trees
For a binary tree T, we can define a flip operation as follows: choose any node, and swap the left and right child subtrees.
A binary tree X is flip equivalent to a binary tree Y if and only if we can make X equal to Y after some number of flip operations.
Given the roots of two binary trees root1 and root2, return true if the two trees are flip equivalent or false otherwise.
406. Queue Reconstruction by Height
You are given an array of people, people, which are the attributes of some people in a queue (not necessarily in order). Each people[i] = [hi, ki] represents the ith person of height hi with exactly ki other people in front who have a height greater than or equal to hi.
Reconstruct and return the queue that is represented by the input array people. The returned queue should be formatted as an array queue, where queue[j] = [hj, kj] is the attributes of the jth person in the queue (queue[0] is the person at the front of the queue).
524. Longest Word in Dictionary through Deleting
Given a string s and a string array dictionary, return the longest string in the dictionary that can be formed by deleting some of the given string characters. If there is more than one possible result, return the longest word with the smallest lexicographical order. If there is no possible result, return the empty string.
247. Strobogrammatic Number II
Given an integer n, return all the strobogrammatic numbers that are of length n. You may return the answer in any order.
A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down).
145. Binary Tree Postorder Traversal
Given the root of a binary tree, return the postorder traversal of its nodes’ values.
144. Binary Tree Preorder Traversal
Given the root of a binary tree, return the preorder traversal of its nodes’ values.
A string is called a happy prefix if is a non-empty prefix which is also a suffix (excluding itself).
Given a string s, return the longest happy prefix of s. Return an empty string “” if no such prefix exists.
1910. Remove All Occurrences of a Substring
Given two strings s and part, perform the following operation on s until all occurrences of the substring part are removed:
- Find the leftmost occurrence of the substring part and remove it from s.
Return s after removing all occurrences of part.
A substring is a contiguous sequence of characters in a string.
You are given a string s. You can convert s to a palindrome by adding characters in front of it.
Return the shortest palindrome you can find by performing this transformation.
459. Repeated Substring Pattern
Given a string s, check if it can be constructed by taking a substring of it and appending multiple copies of the substring together.