leetcode

This year, I met another wave, collected FANMG's offers, and found that the proportion of brushing questions in job hunting is getting lower and lower. There are many reasons for this, but the biggest factor is that it is no longer so difficult for me to solve the questions. Looking back, brushing the questions is actually once and for all, and the harvest after surviving is continuous...

Given a Binary Search Tree and a target number, return true if there exist two elements in the BST s…

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all…

Given a binary tree, determine if it is height-balanced. For this problem, a height-balanced binary …

Given a non-empty binary search tree and a target value, find the value in the BST that is closest t…

Given two binary trees, write a function to check if they are equal or not. Two binary trees are con…

Given a binary tree, return the bottom-up level order traversal of its nodes’ values. (ie, fro…

Given a binary tree, return all root-to-leaf paths. For example, given the following binary tree: 1 …

Find the nth digit of the infinite integer sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, … Note:…

The set S originally contains numbers from 1 to n. But unfortunately, due to the data error, one of …

Write an algorithm to determine if a number is “happy”. A happy number is a number defin…

Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.…

You have a total of n coins that you want to form in a staircase shape, where every k-th row must ha…

Given a positive integer, return its corresponding column title as appear in an Excel sheet. For exa…

Given an integer, write a function to determine if it is a power of two. class Solution { public boo…