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https://leetcode.com/problems/maximum-depth-of-binary-tree/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 far

https://leetcode.com/problems/power-of-three/Given an integer, write a function to determine if it is a power of three.Follow up: Could you do it without using any loop / recursion?3的次方数没有显著的特点，最直接的方法

https://leetcode.com/problems/ugly-number/Write a program to check whether a given number is an ugly number.Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 6, 8

Reverse bits of a given 32 bits unsigned integer.For example, given input 43261596 (represented in binary as 00000010100101000001111010011100), return 964176192 (represented in binary as 00111001011110

https://leetcode.com/problems/single-number/Given an array of integers, every element appears twice except for one. Find that single one.Note: Your algorithm should have a linear runtime complexity. C

https://leetcode.com/problems/missing-number/Given an array containing n distinct numbers taken from 0, 1, 2, …, n, find the one that is missing from the array.For example, Given nums = [0, 1, 3] retu

https://leetcode.com/problems/string-to-integer-atoi/Implement atoi to convert a string to an integer.Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below

https://leetcode.com/problems/reverse-integer/Reverse digits of an integer.Example1: x = 123, return 321 Example2: x = -123, return -321Have you thought about this? Here are some good questions to as

https://leetcode.com/problems/reverse-string/Write a function that takes a string as input and returns the string reversed.Example: Given s = “hello”, return “olleh”.1.char* reverseString(char* s) {

https://leetcode.com/problems/add-digits/Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.For example:Given num = 38, the process is like: 3 + 8 = 11,

https://leetcode.com/problems/power-of-four/Given an integer (signed 32 bits), write a function to check whether it is a power of 4.Example: Given num = 16, return true. Given num = 5, return false.Fo

https://leetcode.com/problems/sum-of-two-integers/Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -.Example: Given a = 1 and b = 2, return 3.注释，这个题目有意思，学过F

https://leetcode.com/problems/invert-binary-tree/Invert a binary tree.4 / \ 2 7 / \ / \ 1 3 6 9 to 4 / \ 7 2 / \ / \ 9 6 3 1给出一棵二叉树，求这棵二叉树的镜像。搬运九章上的实现

https://leetcode.com/problems/move-zeroes/Given an array nums, write a function to move all 0’s to the end of it while maintaining the relative order of the non-zero elements.For example, given nums =

https://leetcode.com/problems/intersection-of-two-arrays/Given two arrays, write a function to compute their intersection.Example: Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2].Note: Each el

https://leetcode.com/problems/contains-duplicate/Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the array

https://leetcode.com/problems/contains-duplicate-ii/Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the

https://leetcode.com/problems/power-of-two/Given an integer, write a function to determine if it is a power of two.数字 2^n 是大于0的，而且等于1左移n位得到的数字，所以2^n与2^n-1 相与运算得到0.bool isPowerOfTwo(int n) { if(n <=

https://leetcode.com/problems/number-of-1-bits/Write a function that takes an unsigned integer and returns the number of ’1’ bits it has (also known as the Hamming weight).For example, the 32-bit integ

https://leetcode.com/problems/counting-bits/Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the number of 1’s in their binary representation and return t

https://leetcode.com/problems/add-binary/Given two binary strings, return their sum (also a binary string).For example, a = “11” b = “1” Return “100”.计算过程类似Verilog的全加器。char* addBinary(char* a, char*

Given a string, find the first non-repeating character in it and return it’s index. If it doesn’t exist, return -1.Examples:s = “leetcode” return 0.s = “loveleetcode”, return 2. Note: You may assume