皮斯特劳沃

Implement int sqrt(int x).Compute and return the square root of x.x is guaranteed to be a non-negative integer.Example 1:Input: 4 Output: 2 Example 2:Input: 8 Output: 2 Explanation: The ...

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.push(x) – Push element x onto stack. pop() – Removes the element on top of the stack. top() – Get t...

Given a non-empty array of integers, return the k most frequent elements.For example, Given [1,1,1,2,2,3] and k = 2, return [1,2].Note: You may assume k is always valid, 1 ≤ k ≤ number of uniqu...

Given four lists A, B, C, D of integer values, compute how many tuples (i, j, k, l) there are such that A[i] + B[j] + C[k] + D[l] is zero.To make problem a bit easier, all A, B, C, D have same lengt...

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. Credits: Special thanks to @fujiaozhu for adding thi

Given two strings s and t which consist of only lowercase letters. String t is generated by random shuffling string s and then add one more letter at a random position. Find the letter that was add

Given two arrays, write a function to compute their intersection. Example: Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2, 2]. Note: Each element in the result should appear as many ti

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. Follow up: Could you solve it withou

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 will be the

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/50768550 Write a function that takes a string as input and returns the string reversed.Example: Given s = “hello”, return “

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/50768550You 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

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/49719255You are a product manager and currently leading a team to develop a new product. Unfortunately, the l

http://blog.youkuaiyun.com/pistolove/article/details/49717803Given a pattern and a string str, find if str follows the same pattern.Here follow means a full mat

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/49432057Given a binary tree, return all root-to-leaf paths.For example, given the following binary tree:

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/49431329Write a program to check whether a given number is an ugly number.Ugly numbers are positive numbers whose p

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/48979767Given two strings s and t, write a function to determine if t is an anagram of s.For example,s = "ana

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/48598939Given an array of n integers where n > 1, nums, return an array output such that output[i] is equal to the pr

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/48598773Implement the following operations of a stack using queues.push(x) -- Push element x onto stack.pop() --

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/48392363Implement the following operations of a queue using stacks.push(x) -- Push element x to the back of queue.pop

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/47334243Given an integer, write a function to determine if it is a power of two.思路：（1）题意为给定一个正整数，判断该正整数是否为2的幂。（2）该题属于Lettcode中的简单题。只需循环判断正整数N对2求余是否为0，如果不为0，返回false;如果

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/47334465Given a singly linked list, determine if it is a palindrome.Follow up:Could you do it in O(n) time and O(1) space?思路：（1）题意为给定一个链表，判断该链表是否“回文”，即该链表中每

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/47334649Write a function to delete a node (except the tail) in a singly linked list, given only access to that node.Supposed the linked list is 1 -> 2 -> 3 -> 4 and you are

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/46868363Find the total area covered by two rectilinear rectangles in a 2D plane.Each rectangle is defined by its bottom left corner and top right corner as shown in the figure.A

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/46868017Reverse bits of a given 32 bits unsigned integer.For example, given input 43261596 (represented in binary as 00000010100101000001111010011100), return 964176192 (represented

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/46762039Given 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：（1）题意为给定

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/46530865Given 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 ch

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/46366207Description:Count the number of prime numbers less than a non-negative number, n.思路：（1）题意为给定整数n，求解n以内的整数中有多少个素数（质数）。（2）该题涉及到数学相关的知识。首先，看下素数的定义：质数（prime

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/45868027Remove all elements from a linked list of integers that have value val.ExampleGiven: 1 --> 2 -->

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/45739753    Reverse a singly linked list.click to show more hints.Hint:A linked list can be reversed either iteratively or recursively. Could you implement both?思

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/45396585Write 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 th

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/44486547Write 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

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/44216867You are given an n x n 2D matrix representing an image.Rotate the image by 90 degrees (clockwise).Follow up:Could you do this in-place?思路：（1）题意为给定一个n*

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/44021767Given 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(

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/43989997Find the contiguous subarray within an array (containing at least one number) which has the largest sum.For example, given the array [−2,1,−3,4,−1,2,1,−5,4],the

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/43854597Given an unsorted array of integers, find the length of the longest consecutive elements sequence.For example,Given [100, 4, 200, 1, 3, 2],The longest consecutive elemen

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/43835055Follow up for "Remove Duplicates":What if duplicates are allowed at most twice?For example,Given sorted array

本文是在学习中的总结，欢迎转载但请注明出处：http://write.blog.youkuaiyun.com/postedit/43740415Say you have an array for which the ith element is the price of a given stock on day i.Design an algori

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/43739647Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.You

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/43532817Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right;

本文是在学习中的总结，欢迎转载但请注明出处：http://blog.youkuaiyun.com/pistolove/article/details/43415313A peak element is an element that is greater than its neighbors.Given an input array where num[i] ≠ num[i+1], find a peak element and return its index.The a