[LeetCode]Pascal's Triangle II 解题报告 标签(空格分隔): LeetCode 题目地址:https://leetcode.com/problems/pascals-triangle-ii/description/ 题目描述: 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 yo…

[LeetCode]731. My Calendar II 解题报告(Python) 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/my-calendar-ii/description/ 题目描述: Implement a MyCalendarTwo class to store your events. A new event can be added if…

[LeetCode]137. Single Number II 解题报告(Python) 标签: LeetCode 题目地址:https://leetcode.com/problems/single-number-ii/description/ 题目描述: Given an array of integers, every element appears three times except for one, which appears exactly once. Find that singl…

[LeetCode]227. Basic Calculator II 解题报告(Python) 标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.me/ 题目地址:https://leetcode.com/problems/basic-calculator-ii/description/ 题目描述: Implement a basic calculator to evaluate a simple exp…

[LeetCode]113. Path Sum II 解题报告(Python) 标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.me/ 题目地址:https://leetcode.com/problems/path-sum-ii/description/ 题目描述: Given a binary tree and a sum, find all root-to-leaf paths where each…

Given a linked list, return the node where the cycle begins. If there is no cycle, return null. Follow up: Can you solve it without using extra space? 思路:由[Leetcode]Linked List Cycle可知.利用一快一慢两个指针可以推断出链表是否存在环路. 如果两个指针相遇之前slow走了s步,则fast走了2s步.而且fast已经在长…

[题意] 输出N皇后问题的解法个数. [题解] 解法一:传统dfs回溯,模拟Q放置的位置即可,应该不难,虽然能通过,但是时间复杂度很高. 解法二:位运算大法好! 首先要明白这道题里两个核心的位运算 1.x & -x 代表除最后一位 1 保留,其它位全部为 0(这个是不是很熟悉,就是树状数组的lowbit哦) 这里要明白计算机存储数的时候存储的是补码,假设x为0101000,正数的补码还是正数,-x为1101000,其补码为1011000,然后0101000 & 1011000,就是保留x的…

Single Number I : Given an array of integers, every element appears twice except for one. Find that single one. Note: Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory? Solution: 解法不少,贴一种: class…

Difficulty:easy  More:[目录]LeetCode Java实现 Description Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number. The function twoSum should return indices of the two numbe…

Difficulty:easy  More:[目录]LeetCode Java实现 Description https://leetcode.com/problems/valid-palindrome-ii/ Given a non-empty string s, you may delete at most one character. Judge whether you can make it a palindrome. Example 1: Input: "aba" Output…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 全排列函数 回溯法 日期 题目地址:https://leetcode.com/problems/n-queens-ii/description/ 题目描述 The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queen…

N-Queens II Follow up for N-Queens problem. Now, instead outputting board configurations, return the total number of distinct solutions. 简单的回溯法. cur[i] == j 代表第i行的皇后位于第j列. 对于每一行,尝试所有列, 如果当前行尝试的位置不与前面所有行的位置冲突,则可以递归到下一行. class Solution { public: int to…

题目 给定一个二叉树和一个目标和,找到所有从根节点到叶子节点路径总和等于给定目标和的路径. 说明: 叶子节点是指没有子节点的节点. 示例: 给定如下二叉树,以及目标和 sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ / \ 7 2 5 1 返回: [ [5,4,11,2], [5,8,4,5] ] 本题同[剑指Offer]面试题34. 二叉树中和为某一值的路径 思路一:回溯 代码 class Solution { public: vector<vector<int&…

标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ https://leetcode.com/problems/ugly-number-ii/ Total Accepted: 12227 Total Submissions: 54870 Difficulty: Medium Question Write a program to find the n-th ugly number. Ugly num…

Reverse Linked List II Reverse a linked list from position m to n. Do it in-place and in one-pass. For example:Given 1->2->3->4->5->NULL, m = 2 and n = 4, return 1->4->3->2->5->NULL. Note:Given m, n satisfy the following cond…

Jump Game (middle) 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. Determine if you are able to reach the last inde…

Ugly Number II Write a program to find the n-th ugly number. Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 1, 2, 3, 4, 5, 6, 8, 9, 10, 12 is the sequence of the first 10 ugly numbers. Note that 1 is typicall…

Basic Calculator II Implement a basic calculator to evaluate a simple expression string. The expression string contains only non-negative integers, +, -, *, / operators and empty spaces . The integer division should truncate toward zero. You may assu…

Majority Element II 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. Hint: How many majority elements could it possibly have? Do you have a better hint…

House Robber II Note: This is an extension of House Robber. After robbing those houses on that street, the thief has found himself a new place for his thievery so that he will not get too much attention. This time, all houses at this place are arrang…

Course Schedule II 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 1, which is expressed as a pair: [0,1] Given the total number…

Combination Sum II Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each number in C may only be used once in the combination. Note: All numbers (including t…

Palindrome Partitioning II  Given a string s, partition s such that every substring of the partition is a palindrome. Return the minimum cuts needed for a palindrome partitioning of s. For example, given s = "aab",Return 1 since the palindrome p…

Single Number II Given an array of integers, every element appears threetimes except for one. Find that single one. Note:Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory? 解法一:开辟map记录次数 class So…

Word Break II 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. For example, given s = "catsanddog", dict = ["cat",…

Jump Game II 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 is to reach the last index in the minimum nu…

Leetcode59 Spiral Matrix II Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order. For example, Given n = 3, You should return the following matrix: [ [ 1, 2, 3 ], [ 8, 9, 4 ], [ 7, 6, 5 ] ]回型打印整数n.Tips: dr dc…

Unique Paths II Follow up for "Unique Paths": Now consider if some obstacles are added to the grids. How many unique paths would there be? An obstacle and empty space is marked as 1 and 0 respectively in the grid. For example, There is one obsta…

Path Sum II Given 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 / \ 4 8 / / \ 11 13 4 / \ / \ 7 2 5 1 return [ [5,4,11,2], [5,8,4,5] ] 这题是在Path…

这是LeetCode里的第142道题. 题目要求: 给定一个链表,返回链表开始入环的第一个节点. 如果链表无环,则返回 null. 说明:不允许修改给定的链表. 进阶:你是否可以不用额外空间解决此题? 起初我在做这道题的时候,以为挺简单的,以为循环链表都是已头节点为循环头,结果... ~~~~(>_<)~~~~ 没考虑到链中任一个节点都可能是循环头的头节点. 一开始比较贪心,就只设置的一个指针p来判断是否循环,结果思考不充分,没考虑到第二种特殊的情况,导致错了很多次. 然后经过多次测试后终于成…