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问题描述：Given a sorted array of integers, find the starting and ending position of a given target value.Your algorithm's runtime complexity must be in the order of O(log n).If the target is

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

问题描述：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.代码示例：/** * Definition

问题描述：Implement int sqrt(int x).Compute and return the square root of x.1、开始我想到的是二分法，但是貌似二分法还是超时了。class Solution {public:   int mySqrt(int x)    {       int low = 1;       i

问题描述：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 and ask yourself what are the possib

问题描述：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 version is developed based

问题描述：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. Could you implement it withou

问题描述：Remove all elements from a linked list of integers that have value val.ExampleGiven: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6Return: 1 --> 2 --> 3 --> 4 --> 5简单说就是去掉链表中指定值的算

问题描述：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] return 2.Note:Your algo

问题描述：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, 1 + 1 = 2. Since 2

问题描述：You are playing the following Nim Game with your friend: There is a heap of stones on the table, each time one of you take turns to remove 1 to 3 stones. The one who removes the last stone

问题描述：Given an integer, write a function to determine if it is a power of two.Credits:Special thanks to @jianchao.li.fighter for adding this problem and creating all test cases.思路：如果是po

问题描述：Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times.You may assume that the array is non-empty and the majori

问题描述：You are climbing a stair case. It takes n steps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?Subscribe to

问题描述：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 integer ’11' has binary representa

问题描述：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 = [0, 1, 0, 3, 12], after

问题描述：Reverse digits of an integer.Example1: x = 123, return 321Example2: x = -123, return -321click to show spoilers.Have you thought about this?Here are some good questions to a

问题描述：Rotate an array of n elements to the right by k steps.For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to[5,6,7,1,2,3,4]. Note:Try to come up as many soluti

问题描述：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 are ugly while 14 is no

问题描述：Invert a binary tree. 4 / \ 2 7 / \ / \1 3 6 9to 4 / \ 7 2 / \ / \9 6 3 1思路：基础题目，提供两个版本：递归和非递归版本JAVA代码：递归版本：public class Soluti

问题描述：Given a pattern and a string str, find if str follows the same pattern.Here follow means a full match, such that there is a bijection between a letter in pattern and a non-empty wor

问题描述：Given two strings s and t, write a function to determine if t is an anagram of s.For example,s = "anagram", t = "nagaram", return true.s = "rat", t = "car", return false.Note:

问题描述：Compare two version numbers version1 and version2.If version1 > version2 return 1, if version1 version2 return -1, otherwise return 0.You may assume that the version strings are non-e

问题描述：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 def

问题描述：Given a binary tree, return all root-to-leaf paths.For example, given the following binary tree: 1 / \2 3 \ 5All root-to-leaf paths are:["1->2->5", "1->3"]

问题描述：Given a positive integer, return its corresponding column title as appear in an Excel sheet.For example: 1 -> A 2 -> B 3 -> C ... 26 -> Z 27 -> AA 28 -> AB

问题描述：Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive.Example:Given nums = [-2, 0, 3, -5, 2, -1]sumRange(0, 2) -> 1sumRange(2, 5) -

问题描述：You are playing the following Bulls and Cows game with your friend: You write down a number and ask your friend to guess what the number is. Each time your friend makes a guess, you provi

问题描述：Given a sorted integer array without duplicates, return the summary of its ranges.For example, given [0,1,2,4,5,7], return ["0->2","4->5","7"].思路：两个指针 s,e .  如果nums[e+1] = nums[e]+1

问题描述：Implement the following operations of a queue using stacks.push(x) -- Push element x to the back of queue.pop() -- Removes the element from in front of queue.peek() -- Get the front ele

问题描述：Implement the following operations of a stack using queues.push(x) -- Push element x onto stack.pop() -- Removes the element on top of the stack.top() -- Get the top element.empty() -- Re

问题描述：Count the number of prime numbers less than a non-negative number, n.返回n之前所有素数的个数。思路：朴素算法代码1显然不满足，初始想法就是朴素算法，没有通过，代码2为埃拉托斯特尼筛法，可以AC。代码1：初始想法：class Solution {public: int countPr

问题描述：Determine whether an integer is a palindrome. Do this without extra space.思路：1、求出位数；2、取出数的第一位和最后一位比较，若相同，将第一位和最后一位同时去掉，然后将base维度降低100，再比较新数的头尾，如此循环下去；如果不等，直接返回false。代码：代码1class Solu

问题描述：Given two strings s and t, determine if they are isomorphic.Two strings are isomorphic if the characters in s can be replaced to get t.All occurrences of a character must be replace

问题描述：Write an algorithm to determine if a number is "happy".A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of

问题描述：Given an integer n, return the number of trailing zeroes in n!.计算n！中0的个数。思路:对n!做质因数分解n!=2x*3y*5z*...显然0的个数等于min(x,z)，并且min(x,z)==z证明：对于阶乘而言，也就是1*2*3*...*n[n/k]代表1~n中

问题描述：Given a roman numeral, convert it to an integer.Input is guaranteed to be within the range from 1 to 3999.思路：纯模拟：基本字符IVXLCDM相应的

问题描述：Given an array and a value, remove all instances of that value in place and return the new length.The order of elements can be changed. It doesn't matter what you leave beyond the new l

问题描述：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 difference between i and j is at mo

问题描述：You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adj