Step-BY-Step

摘要： 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 fo... 阅读全文

摘要： Implementatoito convert a string to an integer.Hint:Carefully consider all possible input cases. If you want a challenge, please do not see below and ... 阅读全文

摘要： Determine whether an integer is a palindrome. Do this without extra space.click to show spoilers.Some hints:Could negative integers be palindromes? (ie, -1)If you are thinking of converting the integer to string, note the restriction of using extra space.You could also try reversing an integer. Howe 阅读全文

摘要： Givennnon-negative integersa1,a2, ...,an, where each represents a point at coordinate (i,ai).nvertical lines are drawn such that the two endpoints of lineiis at (i,ai) and (i, 0). Find two lines, which together with x-axis forms a container, such that the container contains the most water.Note: You 阅读全文

摘要： Write a function to find the longest common prefix string amongst an array of strings.一个个比就行了，找到最长的匹配子串。 1 public class Solution { 2 public String longestCommonPrefix(String[] strs) { 3 // Note: The Solution object is instantiated only once and is reused by each test case. 4 if(s... 阅读全文

摘要： 转自 http://tech-wonderland.net/blog/summary-of-ksum-problems.html前言:做过leetcode的人都知道, 里面有2sum, 3sum(closest), 4sum等问题, 这些也是面试里面经典的问题, 考察是否能够合理利用排序这个性质, 一步一步得到高效的算法. 经过总结, 本人觉得这些问题都可以使用一个通用的K sum求和问题加以概括消化, 这里我们先直接给出K Sum的问题描述和算法(递归解法), 然后将这个一般性的方法套用到具体的K, 比如leetcode中的2Sum, 3Sum, 4Sum问题. 同时我们也给出另一种哈希算法 阅读全文

摘要： Given an arraySofnintegers, are there elementsa,b,c, anddinSsuch thata+b+c+d= target? Find all unique quadruplets in the array which gives the sum of target.Note:Elements in a quadruplet (a,b,c,d) must be in non-descending order. (ie,a≤b≤c≤d)The solution set must not contain duplicate quadruplets. . 阅读全文

摘要： Given an arraySofnintegers, find three integers inSsuch that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exactly one solution. For example, given array S = {-1 2 1 -4}, and target = 1. The sum that is closest to ... 阅读全文