emmaalways的专栏

Problem：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 possible

Problem:Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring.分析：最长回

Problem:Given n non-negative integers a1, a2, ..., an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of line i is at (i, ai) and (i,

Problem:Implement strStr().Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.分析：int strStr(char* haystack, char* needle) 的作用是寻找needle

Problem: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 leng

Problem:Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length.Do not allocate extra space for another array, you must do this in pl

Problem:Write a function to find the longest common prefix string amongst an array of strings.分析：题目非常简单明了：求一组字符串的最长前缀。指明是前缀，只需将各个字符串中字符一一比较即可。有两种比较方式：1、两两比较，再将前缀结果与下一个比较。2、依次比较第i位上所有字符

Problem:Determine whether an integer is a palindrome. Do this without extra space.Some hints:Could negative integers be palindromes? (ie, -1)If you are thinking of converting the integer to st

Problem:Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.分析：归并排序的最后一个步骤。链表的归并的一个好处是当一个链表已经NULL时，只需

Problem:The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)P A H

Problem:Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.The brackets must close in the correct order, "()" and "()[]{}" are

Problem：Reverse digits of an integer.Example1: x = 123, return 321Example2: x = -123, return -321Have you thought about this?Here are some good questions to ask before coding. Bonus poin

Problem:Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters for "abcabcbb" is "abc", which the length

Problem：Given a linked list, remove the nth node from the end of list and return its head.For example, Given linked list: 1->2->3->4->5, and n = 2. After removing the second node from the

Problem:Given an array of integers, find two numbers such that they add up to a specific target number.The function twoSum should return indices of the two numbers such that they add up to the tar

Problem:You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return

Problem:Given an integer, convert it to a roman numeral.Input is guaranteed to be within the range from 1 to 3999.分析：题目的要点在于罗马数字规则，见百度百科中罗马数字词条。剩下的就是写出与规则对应的逻辑。AC Code(C++):cla