一步一脚印

leetcode        541. Reverse String II           Given a string and an integer k, you need to reverse the first k characters for every 2k characters counting from the start of the string. If there a

leetcode   387. First Unique Character in a StringGiven 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"re

leetcode        350. Intersection of Two Arrays II      Given two arrays, write a function to compute their intersection. Example:Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return[2, 2]. No

leetcode       206. Reverse Linked List        Reverse a singly linked list.   无头节点AC:/** * Definition for singly-linked list. * struct ListNode { *     int val; *     stru

leetcode  404. Sum of Left Leaves           Find the sum of all left leaves in a given binary tree.Example: 3 / \ 9 20 / \ 15 7There are two left leaves in the binary tre

leetcode     383. Ransom Note           Given an arbitrary ransom note string and another string containing letters from all the magazines, write a function that will return true if the ransom note

leetcode  349. 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:

leetcode    453. Minimum Moves to Equal Array Elements           Given a non-empty integer array of size n, find the minimum number of moves required to make all array elements equal, where a move

leetcode   455. Assign Cookies           Assume you are an awesome parent and want to give your children some cookies. But, you should give each child at most one cookie. Each child i has a greed fa

leetcode  167. Two Sum II - Input array is sorted           Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number

leetcode   506. Relative Ranks           Given scores of N athletes, find their relative ranks and the people with the top three highest scores, who will be awarded medals: "Gold Medal", "Silver Med

leetcode       122. Best Time to Buy and Sell Stock II           Say you have an array for which the ith element is the price of a given stock on dayi.Design an algorithm to find the maximum p

leetcode     171. Excel Sheet Column Number           Related to question Excel Sheet Column TitleGiven a column title as appear in an Excel sheet, return its corresponding column number.For

leetcode   237. Delete Node in a Linked ListWrite 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 ->

leetcode         551. Student Attendance Record I           You are given a string representing an attendance record for a student. The record only contains the following three characters:

leetcode      268. 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,

leetcode       447. Number of Boomerangs          Given n points in the plane that are all pairwise distinct, a "boomerang" is a tuple of points(i, j, k) such that the distance between i and j e

leetcode   13. Roman to Integer          Given a roman numeral, convert it to an integer.Input is guaranteed to be within the range from 1 to 3999.AC:int trans(char a){    int add;   

leetcode    217. Contains DuplicateGiven 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, and it sh

leetcode    409. Longest PalindromeGiven a string which consists of lowercase or uppercase letters, find the length of the longest palindromes that can be built with those letters.This is case s

leetcode      504. Base 7   Given an integer, return its base 7 string representation.Example 1:Input: 100Output: "202"Example 2:Input: -7Output: "-10"Note: The input

leetcode  242. Valid AnagramGiven 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", ret

leetcode    169. Majority Element          Given an array of size n, find the majority element. The majority element is the element that appearsmore than ⌊ n/2 ⌋ times.You may assume that the

leetcode    100. Same Tree           Given two binary trees, write a function to check if they are equal or not. Two binary trees are considered equal if they are structurally identical and the no

leetcode   530. Minimum Absolute Difference in BST           Given a binary search tree with non-negative values, find the minimum absolute difference between values of any two nodes.Example:

leetcode    563. Binary Tree Tilt           Given a binary tree, return the tilt of the whole tree.The tilt of a tree node is defined as the absolute difference between the sum of all left subtr

leetcode  292. Nim GameYou 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 t

leetcode  463. Island PerimeterYou are given a map in form of a two-dimensional integer grid where 1 represents land and 0 represents water. Grid cells are connected horizontally/vertically (not d

You are given two arrays (without duplicates) nums1 andnums2 where nums1’s elements are subset of nums2. Find all the next greater numbers fornums1's elements in the corresponding places of nums2.

leetcode   344. Reverse String           Write a function that takes a string as input and returns the string reversed.Example:Given s = "hello", return "olleh". AC:char* reverseString

leetcode  412. Fizz Buzz          Write a program that outputs the string representation of numbers from 1 to n.But for multiples of three it should output “Fizz” instead of the number and for

leetcode 500. Keyboard RowGiven a List of words, return the words that can be typed using letters of alphabet on only one row's of American keyboard like the image below. Example 1

leetcode  476. Number ComplementGiven a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation.Note:The given integer is gua

leetcode     557. Reverse Words in a String III           Given a string, you need to reverse the order of characters in each word within a sentence while still preserving whitespace and initial w

leetcode  566. Reshape the MatrixIn MATLAB, there is a very useful function called 'reshape', which can reshape a matrix into a new one with different size but keep its original data.You're gi

leetcode 461. Hamming Distance          The Hamming distance between two integers is the number of positions at which the corresponding bits are different.Given two integers x and y, calculate

leetcode  485. Max Consecutive Ones          Given a binary array, find the maximum number of consecutive 1s in this array.Example 1:Input: [1,1,0,1,1,1]Output: 3Explanation: The first two

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 without using extra

leetcode  520. Detect Capital          Given a word, you need to judge whether the usage of capitals in it is right or not.We define the usage of capitals in a word to be right when one of the f

leetcode   492. Construct the Rectangle           For a web developer, it is very important to know how to design a web page's size. So, given a specific rectangular web page’s area, your job by now