乐胖代购免代理版

[LeetCode]Path Sum

Question Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.For example: Given the below binary tree a

leetcode

递归

子树

复杂度

转载 2023-02-02 14:56:14 35 阅读

[LeetCode]Path Sum II

QuestionGiven a binary tree and a sum, find all root-to-leaf paths where each path’s sum equals the given sum.For example: Given the below binary tree and sum = 22, 5 / \

leetcode

List

复杂度

递归

原创 2023-02-02 14:56:07 50 阅读

[LeetCode]Best Time to Buy and Sell Stock

Question Say you have an array for which the ith element is the price of a given stock on day i.If you were only permitted to c

leetcode

Math

最小值

复杂度

原创 2023-02-02 14:56:03 120 阅读

[LeetCode]Populating Next Right Pointers in Each Node II

QuestionFollow up for problem “Populating Next Right Pointers in Each Node”.What if the given tree could be any binary tree? Woul

leetcode

子节点

父节点

复杂度

原创 2023-02-02 14:55:59 90 阅读

关于树的深度和高度的计算

关于树的深度和高度的计算，我看到两个不同的说法，它们的区别就在于到底是从0开始计算还是从1开始计算。（网上的和算法题偏向说法二，如果有能找到更加权威的解答望不吝赐教）说法一《数据结构与算法分析：C语言描述》第2版中的第4.1节中：说法二来自：树的高度和深度的区别K节点在树的底层，是一个叶子节点，则一般定义为K的高度在最低为1，以此类推，O的高度也是为1，P的节点也是为1。M节点是叶子节点O

数据结构

算法

子节点

结点

父节点

原创 2023-02-02 14:55:29 715 阅读

[LeetCode]Construct Binary Tree from Preorder and Inorder Traversal

Question Given preorder and inorder traversal of a tree, construct the binary tree.Note: You may assume that duplicates do not exist in the tree.本题难度Medium。二分法【复杂度】时间 O(N) 空间 O(N) 【思路】我们先考察先序遍历

leetcode

遍历

子树

先序遍历

中序遍历

转载 2023-02-02 14:55:22 65 阅读

[LeetCode]Flatten Binary Tree to Linked List

Question Given a binary tree, flatten it to a linked list in-place.For example, Given 1 / \ 2 5 / \ \ 3 4 6The flattened tree should look like: 1 \

leetcode

子树

复杂度

List

转载 2023-02-02 14:55:16 44 阅读

[LeetCode]Construct Binary Tree from Inorder and Postorder Traversal

QuestionGiven inorder and postorder traversal of a tree, construct the binary tree.Note: You may assume that duplicates do not exist in the tree.本题难度Medium。二分法【复杂度】时间 O(N) 空间 O(N) 【思路】与[LeetCode

leetcode

遍历

子树

二分法

复杂度

原创 2023-02-02 14:55:13 89 阅读

[LeetCode]Populating Next Right Pointers in Each Node

Question Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; Tr

leetcode

父节点

递归

复杂度

原创 2023-02-02 14:55:08 78 阅读

[LeetCode]Pascal's Triangle

Question Given numRows, generate the first numRows of Pascal’s triangle.For example, given numRows = 5, Return[ [1], [1,1], [1,2,1]

leetcode

List

i++

Pascal

原创 2023-02-02 14:55:04 63 阅读

[LeetCode]Pascal's Triangle II

Question Given an index k, return the kth row of the Pascal’s triangle.For example, given k = 3, Return [1,3,3,1].Note: Could you optimizsy。【复杂度】

leetcode

List

Pascal

复杂度

原创 2023-02-02 14:54:59 64 阅读

[LeetCode]Sum Root to Leaf Numbers

Question Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number.An example is t

leetcode

子节点

子树

复杂度

原创 2023-02-02 14:54:56 54 阅读

（复习）[LeetCode]Word Ladder

Question Given two words (beginWord and endWord), and a dictionary’s word list, find the length of shortest transformationnged

leetcode

dictionary

List

ci

复杂度

原创 2023-02-02 14:54:51 86 阅读

[LeetCode]Triangle

Question Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbersiangle [ [2], [3,4],

leetcode

path

List

Math

复杂度

原创 2023-02-02 14:54:44 74 阅读

[LeetCode]Best Time to Buy and Sell Stock II

Question 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 maxim

leetcode

贪心法

复杂度

i++

原创 2023-02-02 14:54:41 51 阅读

[LeetCode]Valid Palindrome

Question Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.For example,

leetcode

ide

git

复杂度

原创 2023-02-02 14:54:35 85 阅读

[LeetCode]Surrounded Regions

Question 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 into 'X's in that surrounded region.For example, X X

leetcode

算法

Pair

i++

搜索

原创 2023-02-02 14:54:32 53 阅读

[LeetCode]Binary Tree Maximum Path Sum

Question Given a binary tree, find the maximum path sum.For this problem, a path is defined as any sequence of nodehild connections.

leetcode

path

子树

Math

复杂度

原创 2023-02-02 14:54:27 47 阅读

[LeetCode]Linked List Cycle

Question Given a linked list, determine if it has a cycle in it.Follow up: Can you solve it without using extra space?本题难度Easy。有2种算法分别是：集合法和快慢指针法1、集合法【复杂度】时间 O(N) 空间 O(N) 【思路】看本节点cur是否在集合内，如果不

leetcode

算法

复杂度

快慢指针

两个指针

原创 2023-02-02 14:54:23 73 阅读

[LeetCode]Best Time to Buy and Sell Stock III

Question 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 m

leetcode

算法

Math

i++

复杂度

原创 2023-02-02 14:54:19 77 阅读

[LeetCode]Gas Station

Question 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 un

leetcode

ci

复杂度

数组

原创 2023-02-02 14:54:14 78 阅读

[LeetCode]Clone Graph

Question Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.OJ’s undirected graph sor eac

leetcode

复杂度

Graph

List

原创 2023-02-02 14:54:10 50 阅读

[LeetCode]Single Number

Question Given an array of integers, every element appears twice except for one. Find that single one.Note: Your algorithm should have a linear runtim

leetcode

复杂度

原创 2023-02-02 14:54:06 71 阅读

[LeetCode]Reorder List

Question 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- it to

leetcode

链表

复杂度

快慢指针

原创 2023-02-02 14:54:02 66 阅读

（复习）[LeetCode]Single Number II

Question Given an array of integers, every element appears three times except for one. Find that single one.Note: Your algorithm should have a linear runtime complexity. Could you implement it withou

leetcode

d3

复杂度

位运算

原创 2023-02-02 14:53:27 77 阅读

[LeetCode]Word Break

Question Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words.For example, given s = "leetcode", dict = ["

leetcode

复杂度

数组

i++

原创 2023-02-02 14:53:23 59 阅读

[LeetCode]Linked List Cycle II

Question Given a linked list, return the node where the cycle begins. If there is no cycle, return null.Note: Do not modify the linked list.Follow up: Can you solve it without using extra space?本题难度M

leetcode

it

复杂度

链表

快慢指针

原创 2023-02-02 14:53:18 78 阅读

[LeetCode]Insertion Sort List

Question本题难度Medium。有2种算法分别是：递归法（省时不省空间）和迭代法（省空间不省时间）1、递归法【复杂度】时间 O(N) 空间 O(N) 函数栈深度【思路】由于链表只能向后走，因此将较大值往后插入。先对子链表head.next进行排序，然后再将head插入到合适的位置，递归进行。【代码】public class Solution { public ListNo

leetcode

函数

递归

链表

算法

原创 2023-02-02 14:53:13 84 阅读

[LeetCode]Candy

Question 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 requirements:Each child must have at least

leetcode

贪心法

Math

复杂度

转载 2023-02-02 14:53:09 74 阅读

[LeetCode]Sort List

Question Sort a linked list in O(n log n) time using constant space complexity.本题难度Medium。归并【复杂度】时间 O(Nlog(N)) 空间 O(1) 【思路】题目要求时间复杂度O(Nlog(N)) 常数空间。对于单向链表适合用归并排序，双向链表适合用快速排序。【注意】第4行的检测是不可或缺的，否

归并排序

leetcode

链表

快速排序

复杂度

原创 2023-02-02 14:53:05 114 阅读

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[LeetCode]Path Sum

[LeetCode]Path Sum II

[LeetCode]Best Time to Buy and Sell Stock

[LeetCode]Populating Next Right Pointers in Each Node II

关于树的深度和高度的计算

[LeetCode]Construct Binary Tree from Preorder and Inorder Traversal

[LeetCode]Flatten Binary Tree to Linked List

[LeetCode]Construct Binary Tree from Inorder and Postorder Traversal

[LeetCode]Populating Next Right Pointers in Each Node

[LeetCode]Pascal's Triangle

[LeetCode]Pascal's Triangle II

[LeetCode]Sum Root to Leaf Numbers

（复习）[LeetCode]Word Ladder

[LeetCode]Triangle

[LeetCode]Best Time to Buy and Sell Stock II

[LeetCode]Valid Palindrome

[LeetCode]Surrounded Regions

[LeetCode]Binary Tree Maximum Path Sum

[LeetCode]Linked List Cycle

[LeetCode]Best Time to Buy and Sell Stock III

[LeetCode]Gas Station

[LeetCode]Clone Graph

[LeetCode]Single Number

[LeetCode]Reorder List

（复习）[LeetCode]Single Number II

[LeetCode]Word Break

[LeetCode]Linked List Cycle II

[LeetCode]Insertion Sort List

[LeetCode]Candy

[LeetCode]Sort List

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