leetcode-java

leetcode-java 二进制求和

二进制求和题目描述：给定两个二进制字符串，返回他们的和（用二进制表示）。输入为非空字符串且只包含数字1和0。示例1:输入:a="11",b="1"输出:"100"示例2:输入:a="1010",b="1011"输出:"10101"问题分析：关于这个题，有两种大的解题思路：1，作为使用java解答的算法题，可以直接使用字符函数进行操作，借助StringBuilderres=newStringBuil
宝宝辉AD·2020-07-11 20:00

Leetcode-Java(四)

31.NextPermutation分三步:https://leetcode.com/problems/next-permutation/solution/1、首先找到相邻的两个元素，前面一个元素值小于后面一个元素值，即nums[i]=0&&nums[i+1]=0){intj=nums.length-1;while(j>=0&&nums[j]=2?dp[i-2]:0)+2;}elseif(i-dp
文哥的学习日记·2020-07-06 00:15

Implement strStr()-leetcode-java

28.ImplementstrStr()-leetcode-java发表于2016/02/06题意ImplementstrStr().Returnstheindexofthefirstoccurrenceofneedleinhaystack
靠靠的博客·2020-07-02 01:24

leetcode-java 有效的数独

有效的数独题目描述：leetcode36.有效的数独*判断一个9x9的数独是否有效。只需要根据以下规则，验证已经填入的数字是否有效即可。数字1-9在每一行只能出现一次。数字1-9在每一列只能出现一次。数字1-9在每一个以粗实线分隔的3x3宫内只能出现一次。上图是一个部分填充的有效的数独。数独部分空格内已填入了数字，空白格用'.'表示。示例1:输入:[["5","3",".",".","7","."
宝宝辉AD·2020-06-25 22:10

Leetcode-Java(十九)

181.EmployeesEarningMoreThanTheirManagers#WriteyourMySQLquerystatementbelowselectt1.NameasEmployeefrom(select*fromEmployee)t1innerjoin(select*fromEmployee)t2ont1.ManagerId=t2.Idwheret1.Salary>t2.Salar
文哥的学习日记·2020-06-25 10:52

Leetcode-Java(二十七)

263.UglyNumberclassSolution{publicbooleanisUgly(intnum){if(num==1)returntrue;if(num==0)returnfalse;while(num%2==0)num=num>>1;while(num%3==0)num=num/3;while(num%5==0)num=num/5;returnnum==1;}}264.UglyNu
文哥的学习日记·2020-06-23 08:06

Leetcode-Java(十八)

171.ExcelSheetColumnNumberclassSolution{publicinttitleToNumber(Strings){if(s==null||s.length()==0)return0;intres=0;for(inti=0;istack;publicBSTIterator(TreeNoderoot){stack=newStack();if(root!=null){Tre
文哥的学习日记·2020-06-23 05:36

【LeetCode-Java实现】15. 3Sum

15.3Sum题目描述思路实现题目描述Givenanarraynumsofnintegers,arethereelementsa,b,cinnumssuchthata+b+c=0?Findalluniquetripletsinthearraywhichgivesthesumofzero.Note:Thesolutionsetmustnotcontainduplicatetriplets.给一个整数
IT Crowd·2020-06-22 21:42

leetcode-java 反转字符串

反转字符串反转字符串I题目描述：leetcode344.反转字符串编写一个函数，其作用是将输入的字符串反转过来。输入字符串以字符数组char[]的形式给出。不要给另外的数组分配额外的空间，你必须原地修改输入数组、使用O(1)的额外空间解决这一问题。你可以假设数组中的所有字符都是ASCII码表中的可打印字符。示例1：输入：["h","e","l","l","o"]输出：["o","l","l","e
宝宝辉AD·2020-06-21 06:51

LeetCode-Java解题常用类方法-持续更新中

开刷LeetCode，把一些Java中常用类的方法，归纳整理，方便今后查阅。不断更新中。。。。。。字符串String转int、long等publicvoidtest(){StringsInt="123";ints=Integer.parseInt(sInt);longls=Long.parseLong(sInt);System.out.println(s+""+ls);}StringBufferS
tikyle·2020-03-27 15:15

Leetcode-Java(十三)

121.BestTimetoBuyandSellStock如果把数组中的两个数两两作差，那么这道题跟求数组中的和最大的子序列是相同的，我们可以参照前面的题的做法。classSolution{publicintmaxProfit(int[]prices){if(prices==null||prices.length=0;i--){desc[i]=Math.max(maxprice-prices[i]
文哥的学习日记·2019-12-11 19:28

leetcode-java 删除排序链表中的重复元素II

删除排序链表中的重复元素II删除排序链表中的重复元素I题目描述：给定一个排序链表，删除所有含有重复数字的节点，只保留原始链表中没有重复出现的数字。示例1:输入:1->2->3->3->4->4->5输出:1->2->5示例2:输入:1->1->1->2->3输出:2->3问题分析：比着之前的删除排序链表的重复元素I，来说，它不需要保留重复的所有元素，一旦发现重复，所有元素都要删除第一种方法：双指针
宝宝辉AD·2019-11-15 14:07

[Leetcode-java] 1160. Find Words That Can Be Formed by Characters

一、问题链接：https://leetcode.com/problems/find-words-that-can-be-formed-by-characters/Example1:Input:words=["cat","bt","hat","tree"],chars="atach"Output:6Explanation:Thestringsthatcanbeformedare"cat"and"ha
喵喵喵1221·2019-08-20 23:07

[Leetcode-java] 1160. Find Words That Can Be Formed by Characters

一、问题链接：https://leetcode.com/problems/find-words-that-can-be-formed-by-characters/Example1:Input:words=["cat","bt","hat","tree"],chars="atach"Output:6Explanation:Thestringsthatcanbeformedare"cat"and"ha
喵喵喵1221·2019-08-20 23:07

[Leetcode-java] 56. Merge Intervals：计算重叠数组

一、问题链接：https://leetcode.com/problems/merge-intervals/问题是针对提出的二维数组，去掉交叉的部分，计算出部分重叠的数组变更点：之前传入的参数为list对象，此次改成了二维数组二、思路：1、先对二维数组中的一维数组左端（类似于线段的起点开始排序）2、根据排序后的数组的值，按顺序遍历遍历数组元素，结合最后合并成功的元素来融合3、合并的情况如下所示：be
喵喵喵1221·2019-08-15 23:47

[Leetcode-java] 56. Merge Intervals：计算重叠数组

一、问题链接：https://leetcode.com/problems/merge-intervals/问题是针对提出的二维数组，去掉交叉的部分，计算出部分重叠的数组变更点：之前传入的参数为list对象，此次改成了二维数组二、思路：1、先对二维数组中的一维数组左端（类似于线段的起点开始排序）2、根据排序后的数组的值，按顺序遍历遍历数组元素，结合最后合并成功的元素来融合3、合并的情况如下所示：be
喵喵喵1221·2019-08-15 23:47

leetcode-java 删除排序链表中的重复元素

删除排序链表中的重复元素题目描述：给定一个排序链表，删除所有重复的元素，使得每个元素只出现一次。示例1:输入:1->1->2输出:1->2示例2:输入:1->1->2->3->3输出:1->2->3问题分析：问题比较简单，判断和下一个结点的值是否相等，相等则跳过直接到下一个元素，直到遇到不等。第一种方法：直接在对head结点操作if(head.val==head.next.val)head.nex
宝宝辉AD·2019-06-22 11:15

【LeetCode-Java实现】53. Maximum Subarray

53.MaximumSubarray题目描述解题思路实现代码题目描述Givenanintegerarraynums,findthecontiguoussubarray(containingatleastonenumber)whichhasthelargestsumandreturnitssum.Example:Input:[-2,1,-3,4,-1,2,1,-5,4],Output:6Explan
IT Crowd·2019-04-27 22:42

Leetcode-Java(十一)

101.SymmetricTree递归求解/***Definitionforabinarytreenode.*publicclassTreeNode{*intval;*TreeNodeleft;*TreeNoderight;*TreeNode(intx){val=x;}*}*/classSolution{publicbooleanisSymmetric(TreeNoderoot){if(root=
文哥的学习日记·2018-03-18 10:43

Leetcode-Java(八)

72.EditDistance动态规划：publicclassSolution{publicintminDistance(Stringword1,Stringword2){intm=word1.length();intn=word2.length();int[][]cost=newint[m+1][n+1];for(inti=0;imap=newHashMap();for(inti=0;i0){f
文哥的学习日记·2018-03-15 11:16

[LeetCode-Java]3. Longest Substring Without Repeating Characters

Givenastring,findthelengthofthelongestsubstringwithoutrepeatingcharacters.Examples:Given“abcabcbb”,theansweris“abc”,whichthelengthis3.Given“bbbbb”,theansweris“b”,withthelengthof1.Given“pwwkew”,theansw
如故1994·2016-09-24 17:56

Implement strStr()-leetcode-java

28.ImplementstrStr()-leetcode-java发表于 2016/02/06题意ImplementstrStr().Returnstheindexofthefirstoccurrenceofneedleinhaystack
hahawhyha·2016-05-06 18:00

Pow(x, n)-leetcode-java

50.Pow(x,n)-leetcode-java发表于 2016/02/06题目Implementpow(x, n). 实现浮点类型的幂运算，x的n次幂。
hahawhyha·2016-05-06 18:00

[LeetCode-JAVA] Course Schedule

题目： There are a total of n courses you have to take, labeled from 0 to n - 1. Some courses may have prerequisites, for example to take course 0 you have to first take course
·2015-10-28 08:54

[LeetCode-JAVA] Binary Tree Inorder Traversal

题目： Given a binary tree, return the inorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3   return [1,3,2].
·2015-10-28 08:54

[LeetCode-JAVA] Majority Element II

题目：Given an integer array of size n, find all elements that appear more than ⌊ n/3 ⌋ times. The algorithm should run in linear time and in O(1) space. 题意：找到数组中权重大于⌊ n/3 ⌋的数字（成为众数）。 思路
·2015-06-29 20:00

[LeetCode-JAVA] Basic Calculator II

题目： Implement a basic calculator to evaluate a simple expression string. The expression string contains only non-negative integers, +, -, *, / operators and empty
·2015-06-29 19:00

[LeetCode-JAVA] The Skyline Problem

题目：题目太长了，见链接-- > The Skyline Problem  Notes: The number of buildings in any input list is guaranteed to be in the range [0, 10000]. The input list is already sorted in ascendi
·2015-06-21 16:00

[LeetCode-JAVA] Invert Binary Tree

题目： Invert a binary tree. 4 / \ 2 7 / \ / \ 1 3 6 9 to 4 / \ 7 2 / \ / \ 9 6 3 1 Trivia:This problem was inspired by this original tweet
·2015-06-20 12:00

[LeetCode-JAVA] Implement Stack using Queues

题目： 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()
·2015-06-20 11:00

[LeetCode-JAVA] Basic Calculator

题目： Implement a basic calculator to evaluate a simple expression string. The expression string may contain open ( and closing parentheses ), the plus + or minus sign -,
·2015-06-20 11:00

[LeetCode-JAVA] Count Complete Tree Nodes

题目： Given a complete binary tree, count the number of nodes. Definition of a complete binary tree from Wikipedia:In a complete binary tree every level, except possibly the last, is co
·2015-06-19 11:00

[LeetCode-JAVA] Shortest Palindrome

题目： Given a string S, you are allowed to convert it to a palindrome by adding characters in front of it. Find and return the shortest palindrome you can find by performing this transformation. For e
·2015-06-18 21:00

[LeetCode-JAVA] Best Time to Buy and Sell Stock IV

题目： Say you have an array for which the ith element is the price of a given stock on day i. Design an algorithm to find the maximum profit. You may complete at most k transa
·2015-06-18 09:00

[LeetCode-JAVA] Word Ladder II

题目： Given two words (start and end), and a dictionary, find all shortest transformation sequence(s) from start to end, such that: Only one letter can be changed at a time
·2015-06-14 14:00

[LeetCode-JAVA] Jump Game II

题目： Given an array of non-negative integers, you are initially positioned at the first index of the array. Each element in the array represents your maximum jump length at that position. Your goal
·2015-06-08 20:00

[LeetCode-JAVA] Substring with Concatenation of All Words

题目： You are given a string, s, and a list of words, words, that are all of the same length. Find all starting indices of substring(s) in s that is a concatenation of each word in&
·2015-06-05 20:00

[LeetCode-JAVA] Reverse Nodes in k-Group

题目： Given a linked list, reverse the nodes of a linked list k at a time and return its modified list. If the number of nodes is not a multiple of k then left-out nodes in the end
·2015-06-05 15:00

[LeetCode-JAVA] Median of Two Sorted Arrays

题目： There are two sorted arrays nums1 and nums2 of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)). 思路
·2015-06-04 20:00

[LeetCode-JAVA] Contains Duplicate IIIMaximal Square

题目： Given a 2D binary matrix filled with 0's and 1's, find the largest square containing all 1's and return its area. For example, given the following matrix: 1 0 1 0 0 1 0 1 1 1 1 1 1 1 1 1 0 0
·2015-06-04 16:00

[LeetCode-JAVA] Contains Duplicate III

题目：Given an array of integers, find out whether there are two distinct indices i and j in the array such that the difference between nums[i] and nums[j] is at m
·2015-06-04 14:00

[LeetCode-JAVA] Add and Search Word - Data structure design

题目： Design a data structure that supports the following two operations: void addWord(word) bool search(word) search(word) can search a literal word or a regular expression string containing only
·2015-06-03 16:00

[LeetCode-JAVA] Course Schedule II

题目： There are a total of n courses you have to take, labeled from 0 to n - 1. Some courses may have prerequisites, for example to take course 0 you have to first take course
·2015-06-02 20:00

[LeetCode-JAVA] Minimum Size Subarray Sum 两种方法(O(n)、O(lgn))

题目： Given an array of n positive integers and a positive integer s, find the minimal length of a subarray of which the sum ≥ s. If there isn't one, return 0 instead. For example,
·2015-06-02 10:00

[LeetCode-JAVA] Isomorphic Strings

题目： 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 chara
·2015-06-02 10:00

[LeetCode-JAVA] Implement Trie (Prefix Tree)

题目： Implement a trie with insert, search, and startsWith methods. // Your Trie object will be instantiated and called as such:// Trie trie = new Trie();// trie.insert("somes
·2015-06-02 10:00

[LeetCode-JAVA] Remove Linked List Elements

题目： 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
·2015-06-01 11:00

[LeetCode-JAVA] Bitwise AND of Numbers Range

题目： Given a range [m, n] where 0 <= m <= n <= 2147483647, return the bitwise AND of all numbers in this range, inclusive. For example, given the range [5, 7], you should return 4.  
·2015-06-01 10:00

[LeetCode-JAVA] Number of Islands

题目： Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically.
·2015-06-01 09:00

[LeetCode-JAVA] Word Break II

题目： Given a string s and a dictionary of words dict, add spaces in s to construct a sentence where each word is a valid dictionary word. Return all such possible sentences.
·2015-05-26 10:00
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