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本篇属于数据结构串讲内容。讲真，一说数学我就头大，一看LeetCode就头疼。一 hash242. Valid AnagramGiven two strings s and t, write a function to determine if t is an anagram of s.Example 1:Input: s = "anagram", t = "nagaram"Output: trueExample 2:Input: s = "rat", t = "car"O.

老师在讲完语言模型之前，貌似是助教插入了一堂习题课044-047，专门讲了下动态规划。关于算法我自己是有体会的，不会或者觉得回了过两又忘了。动态规划：很重要的是找出初始数据以及状态转移。补充下题目：53. Maximum SubarrayGiven an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return it

一题目You are given twonon-emptylinked lists representing two non-negative integers. The most significant digit comes first and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.You may assume the two numbers..

一 序本文属于极客时间-算法训练营 学习笔记。对应章节：极客时间-算法训练营 学习笔记 3递归的实现、特性以及思维要点二 70Climbing StairsYou are climbing a stair case. It takesnsteps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?N...

一 序 本文属于极客时间-算法训练营 学习笔记。上节课学习了树、二叉树、二叉搜索树的实现本节课学习做题二二叉树的中序遍历一 题目：94.Binary Tree Inorder TraversalMedium3067130Add to ListShareGiven a binary tree, return theinordertraversal of its nodes' values.Example:Input: [1,null,2,3] 1...

一 题目Given a binary tree, return thepreordertraversal of its nodes' values.Example:Input:[1,null,2,3] 1 \ 2 / 3Output:[1,2,3]Follow up:Recursive solution is trivial, could you do it iteratively?二 分析题目都说了，递归是容易的，能否用迭代实...

一题目Given an n-ary tree, return thepreordertraversal of its nodes' values.Nary-Tree input serializationis represented in their level order traversal, each group of children is separated by the null value (See examples).Follow up:Recursive solu...

一 题目Given an array of sizen, find the majority element. The majority element is the element that appearsmore than⌊ n/2 ⌋times.You may assume that the array is non-empty and the majority elemen...

一 题目Given a non-empty array of integers, return thekmost frequent elements.Example 1:Input: nums = [1,1,1,2,2,3], k = 2Output: [1,2]Example 2:Input: nums = [1], k = 1Output: [1]Note...

一 基础从百科摘个定义：在计算机科学中，二叉树是每个结点最多有两个子树的树结构。通常子树被称作“左子树”（left subtree）和“右子树”（right subtree）。二叉树常被用于实现二叉查找树和二叉堆。一棵深度为k，且有2^k-1个结点的二叉树，称为满二叉树。这种树的特点是每一层上的结点数都是最大结点数。而在一棵二叉树中，除最后一层外，若其余层都是满的，并且或者最后一层是...

一 问题Given a sorted linked list, delete all nodes that have duplicate numbers, leaving onlydistinctnumbers from the original list.Example 1:Input: 1->2->3->3->4->4->5Output:...

一 题目Given a sorted linked list, delete all duplicates such that each element appear onlyonce.Example 1:Input: 1->1->2Output: 1->2Example 2:Input: 1->1->2->3->3Outp...

一 题目Write a program to find the node at which the intersection of two singly linked lists begins.For example, the following two linked lists:begin to intersect at node c1.Example 1:Inpu...

一 问题Given a linked list, determine if it has a cycle in it.To represent a cycle in the given linked list, we use an integerposwhich represents the position (0-indexed)in the linked list where t...

一 题目 Given two wordsword1andword2, find the minimum number of operations required to convertword1toword2.You have the following 3 operations permitted on a word:Insert a character Delet...

一 题目Given anabsolute pathfor a file (Unix-style), simplify it. Or in other words, convert it to thecanonical path.In a UNIX-style file system, a period.refers to the current directory. Furthe...

一 题目You are climbing a stair case. It takesnsteps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?Note:Givennwill be a po...

一 题目Implementint sqrt(int x).Compute and return the square root ofx, wherexis guaranteed to be a non-negative integer.Since the return typeis an integer, the decimal digits are truncated an...

一 题目Given an array of words and a widthmaxWidth, format the text such that each line has exactlymaxWidthcharacters and is fully (left and right) justified.You should pack your words in a greed...

一 题目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). Fi...

3.Longest Substring Without Repeating CharactersGiven a string, find the length of thelongest substringwithout repeating characters.Example 1:Input: "abcabcbb"Output: 3 Explanation: The an...

You are given with a string . Your task is to remove atmost two substrings of any length from the given string such that the remaining string contains vowels('a','e','i','o','u') only. Your aim is the...

Given a stringS, check if the letters can be rearranged so that two characters that are adjacent to each other are not the same.If possible, output any possible result. If not possible, return the...

一 题目Givennropes of different lengths, we need to connect these ropes into one rope. We can connect only 2 ropes at a time. The cost required to connect 2 ropes is equal to sum of their lengths. Th...

A six-sided die is a small cube with a different number of pips on each face (side), ranging from 1 to 6.On any two opposite side of the cube, the number of pips adds up to 7; that is, there are thre...

这个题目是leetcode的premuim 才能看的，网上看到别人贴出来了，学习一下。一 题目原文链接：https://blog.youkuaiyun.com/Csdn_jey/article/details/97611628There are N cities numbered from 1 to N.You are given connections, where each connec...

一 题目Medium 难度A stringSof lowercase letters is given. We want to partition this string into as many parts as possible so that each letter appears in at most one part, and return a list of intege...

You have an array oflogs. Each log is a space delimited string of words.For each log, the first word in each log is an alphanumericidentifier. Then, either:Each word after the identifier will ...

又到了经典top K问题了。We have a list ofpointson the plane. Find theKclosest points to the origin(0, 0).(Here, the distance between two points on a plane is the Euclidean distance.)You may return t...

一 原题There are 8 prison cells in a row, and each cell is either occupied or vacant.Each day, whether the cell is occupied or vacant changes according to the following rules:If a cell has two adja...

easy 模式一题目819Most Common WordGiven a paragraphand a list of banned words, return the most frequent word that is not in the list of banned words. It is guaranteed there is at least one word that...

Longest Common PrefixEASY模式Write a function to find the longest common prefix string amongst an array of strings.If there is no common prefix, return an empty string"".Example 1:Input: ["...

1strStrImplementstrStr().Return the index of the first occurrence of needle in haystack, or-1if needle is not part of haystack.Example 1:Input: haystack = "hello", needle = "ll"Output: 2...

本文属于算法leetcode系列。singleNumber1:easy 模式。Given anon-emptyarray of integers, every element appearstwiceexcept for one. Find that single one.Note:Your algorithm should have a linear runtime c...

一 题目Roman numerals are represented by seven different symbols:I,V,X,L,C,DandM.Symbol ValueI 1V 5X 10L 50C 100D ...

一 题目 Given an arraynumsofnintegers, are there elementsa,b,cinnumssuch thata+b+c= 0? Find all unique triplets in the array which gives the sum of zero.Note:The solution set must...

一 题目Find thekth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element.Example 1:Input: [3,2,1,5,6,4] and k = 2Output:...

一 题目Given an array ofnpositive integers and a positive integers, find the minimal length of acontiguoussubarray of which the sum ≥s. If there isn't one, return 0 instead.Example:Input: s...

一 题目Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n).Example:Input: S = "ADOBECODEBANC", T = "ABC"Output: "BANC"No...

一 题目Given a strings, find the longest palindromic substring ins. You may assume that the maximum length ofsis 1000.Example 1:Input: "babad"Output: "bab"Note: "aba" is also a valid answer....