zhumingyuan111的博客

Guess Number Higher or Lower IIURL : https://leetcode.com/problems/guess-number-higher-or-lower-ii/解题思路：递归的思路是，我可以猜1~n中任意一个数x，然后递归的去猜[1,x) 和（x,n]两段，取他们最大的值。动态规划的思路，自底向上，把长度为[1,2,…,n]的子数组算出来，dp[1]...

描述：Sort a linked list in O(n log n) time using constant space complexity.URLhttps://leetcode.com/problems/sort-list/description/解释如果时间复杂度是nlogn，则需要使用快速排序或者归并排序的思想，下面给出两种算法代码//归并排序/** * Definition

描述：Sort a linked list using insertion sort.URLhttps://leetcode.com/problems/insertion-sort-list/description/解释因为我们的链表是单项的，所以每一次是从头节点向后查找要插入的位置，然后当前节点插入指定位置。代码class Solution { public ListNode insert

URLhttps://leetcode.com/problems/max-points-on-a-line/description/描述Given n points on a 2D plane, find the maximum number of points that lie on the same straight line.解题思路遍历所有点，计算出每一个点与其他的点的

URLhttps://leetcode.com/problems/maximum-gap/description/描述Given an unsorted array, find the maximum difference between the successive elements in its sorted form.Try to solve it in linear time/space.R

URLhttps://leetcode.com/problems/find-minimum-in-rotated-sorted-array/description/描述：Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.(i.e., 0 1 2

URL:https://leetcode.com/problems/find-minimum-in-rotated-sorted-array-ii/description/描述：Follow up for "Find Minimum in Rotated Sorted Array":What if duplicates are allowed?Would this affec

URL：https://leetcode.com/problems/lru-cache/description/描述：Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations: get and put.get(key) -

URLhttps://leetcode.com/problems/candy/description/描述There are N children standing in a line. Each child is assigned a rating value.You are giving candies to these children subjected to the following r

url :https://leetcode.com/problems/reorder-list/description/描述Given a singly linked list L: L0→L1→…→Ln-1→Ln, reorder it to: L0→Ln→L1→Ln-1→L2→Ln-2→…You must do this in-place without altering the nodes’

Urlhttps://leetcode.com/submissions/detail/129718140/描述Given two words (beginWord and endWord), and a dictionary’s word list, find all shortest transformation sequence(s) from beginWord to endWord, suc

URLhttps://leetcode.com/problems/gas-station/description/描述There are N gas stations along a circular route, where the amount of gas at station i is gas[i].You have a car with an unlimited gas tank and

Palindrome PartitioningURLhttps://leetcode.com/problems/palindrome-partitioning/description/描述Given a string s, partition s such that every substring of the partition is a palindrome.Return all possibl

URLhttps://leetcode.com/problems/longest-consecutive-sequence/description/描述Given an unsorted array of integers, find the length of the longest consecutive elements sequence.For example, Given [100, 4

URLhttps://leetcode.com/problems/dungeon-game/description/描述The demons had captured the princess (P) and imprisoned her in the bottom-right corner of a dungeon. The dungeon consists of M x N rooms laid

URLhttps://leetcode.com/problems/contains-duplicate-iii/description/描述Given an array of integers, find out whether there are two distinct indices i and j in the array such that the absolute difference

URLhttps://leetcode.com/problems/shortest-palindrome/description/描述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 pali

URL : https://leetcode.com/problems/subarrays-with-k-different-integers/思路：该题其实代码量不多，但是思路不好想，我是看了discuss才恍然大悟。下面给出代码。数组中最多出现K个不同的数字的组合数为N， 数组中最多出现K-1个不同的数字的组合数为M，则我们想要的结果是出现K个不同的组合数N-M.最多出现K个不同的数字...

URL : https://leetcode.com/problems/longest-substring-without-repeating-characters/思路：思路就是滑动窗口，当前字符在之前没有出现过，则窗口左端和右端都有效，如果出现重复，则移动窗口的左端直到当前位置的字符在字符串[left, current-1]中没有出现过，在变化的过程中记录最大的长度。下面给出代码。代码：...

Url : https://leetcode.com/problems/count-of-smaller-numbers-after-self/You are given an integer array nums and you have to return a new counts array. The counts array has the property where counts[i...

url https://leetcode.com/problems/serialize-and-deserialize-binary-tree/本题使用层次遍历就行了，下面给出代码/** * Definition for a binary tree node. */ static public class TreeNode { int val;...

题目链接：https://leetcode.com/problems/find-median-from-data-stream/解题思路既然是是找到中位数，我们就使用两个堆，一个是大顶堆，一个小顶堆，保证两个堆满足以下条件：大顶堆的第一个元素需要小于小顶堆的第一个元素；大顶堆的元素数量不能小于小顶堆且最多只能多一个元素；满足以上条件，需要找中位数的时候，判断大顶堆是否比小顶堆元素多，如...

题目链接https://leetcode.com/problems/different-ways-to-add-parentheses/描述Given a string of numbers and operators, return all possible results from computing all the different possible ways to group nu...

题目链接 ： https://leetcode.com/problems/the-skyline-problem/解题思路先定义下：对于三元组（left,right,high）我们可以认为（left,high）为开始的先计为（left,high,true）(right,high) 认为结束的点，计为（right,high,false），把数据整理为如上格式之后，把输入的点处理一下，保证排顺...

题目描述Game of LifeMedium647131FavoriteShareAccording to the Wikipedia’s article: “The Game of Life, also known simply as Life, is a cellular automaton devised by the British mathematician John ...

题目描述Given an Iterator class interface with methods: next() and hasNext(), design and implement a PeekingIterator that support the peek() operation – it essentially peek() at the element that will be ...

题目描述Given an array nums containing n + 1 integers where each integer is between 1 and n (inclusive), prove that at least one duplicate number must exist. Assume that there is only one duplicate numbe...

题目描述Given an unsorted array nums, reorder it such that nums[0] < nums[1] > nums[2] < nums[3]…Example 1:Input: nums = [1, 5, 1, 1, 6, 4]Output: One possible answer is [1, 4, 1, 5, 1, 6].E...

Given an array nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only see the k numbers in the window. Each time the sliding window m...

best time buy and sell stock系列最近把leetcode上“best time buy and sell stock”系列一共5个问题整理了一下，题目就补贴出来了，在leetcode上面就能找到。best time buy and sell stock 1public int maxProfit(int[] prices) { if (prices=...

URLhttps://leetcode.com/problems/sum-root-to-leaf-numbers/description/描述Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number.An example is the root-to-le

urlhttps://leetcode.com/problems/surrounded-regions/description/描述Given a 2D board containing ‘X’ and ‘O’ (the letter O), capture all regions surrounded by ‘X’.A region is captured by flipping all ‘O’s

URL：https://leetcode.com/problems/copy-list-with-random-pointer/description/描述：A linked list is given such that each node contains an additional random pointer which could point to any node in the list

URL：https://leetcode.com/problems/subsets-ii/#/description题目大意：Given a collection of integers that might contain duplicates, nums, return all possible subsets.Note: The solution set must not contain du

url :https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii/#/description题目描述Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from th

URLhttps://leetcode.com/problems/gray-code/#/description描述The gray code is a binary numeral system where two successive values differ in only one bit.Given a non-negative integer n representing the tot

URLhttps://leetcode.com/problems/search-in-rotated-sorted-array/#/description描述Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.(i.e., 0 1 2 4 5 6 7 might b

Majority Element链接https://leetcode.com/problems/majority-element/#/description描述Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ t

链接：https://leetcode.com/problems/insert-delete-getrandom-o1/#/description题目描述：Design a data structure that supports all following operations in average O(1) time.insert(val): Inserts an item val to the

url:https://leetcode.com/problems/word-ladder/#/description题目大意：Given two words (beginWord and endWord), and a dictionary’s word list, find the length of shortest transformation sequence from beginWord