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 set 日期 题目地址:https://leetcode-cn.com/problems/destination-city/ 题目描述 给你一份旅游线路图,该线路图中的旅行线路用数组 paths 表示,其中 paths[i] = [cityAi, cityBi] 表示该线路将会从 cityAi 直接前往 cityBi .请你找出这次旅行的终点站,即没有…

In a 2 dimensional array grid, each value grid[i][j] represents the height of a building located there. We are allowed to increase the height of any number of buildings, by any amount (the amounts can be different for different buildings). Height 0 i…

原题地址:https://oj.leetcode.com/problems/reverse-words-in-a-string/ 题意: Given an input string, reverse the string word by word. For example,Given s = "the sky is blue",return "blue is sky the". 解题思路:这题很能体现python处理字符串的强大功能. 代码: class Solut…

在LeetCode上刷一道题,题目如下: 3. 无重复字符的最长子串 给定一个字符串,请你找出其中不含有重复字符的?最长子串?的长度. 示例?1: 输入: "abcabcbb"输出: 3 解释: 因为无重复字符的最长子串是 "abc",所以其长度为 3. 示例 2: 输入: "bbbbb"输出: 1解释: 因为无重复字符的最长子串是 "b",所以其长度为 1. 示例 3: 输入: "pwwkew"输出: 3…

题目 给定一个单词列表,我们将这个列表编码成一个索引字符串 S 与一个索引列表 A. 例如,如果这个列表是 ["time", "me", "bell"],我们就可以将其表示为 S = "time#bell#" 和 indexes = [0, 2, 5]. 对于每一个索引,我们可以通过从字符串 S 中索引的位置开始读取字符串,直到 "#" 结束,来恢复我们之前的单词列表. 那么成功对给定单词列表进行编码的最小…

Problem:You are given an array x of n positive numbers. You start at point (0,0) and moves x[0] metres to the north, then x[1] metres to the west, x[2] metres to the south,x[3] metres to the east and so on. In other words, after each move your direct…

不使用运算符 + 和 - ,计算两整数 a .b 之和. 示例 1: 输入: a = 1, b = 2 输出: 3 示例 2: 输入: a = -2, b = 3 输出: 1 思路 比如\(5+6=11\) 我们可以按照如下步骤: 先不考虑进位为1 考虑进位之后\(10+1=11\) 直到没有进位的情况出现才结束 二进制也是类似处理: 先"按位加",也就是异或,在python中为^ 处理进位,进位就是和,在python中为&,还要左移<<1位 循环上述步骤就好了 要…

给定一个整数数组,判断是否存在重复元素. 如果任何值在数组中出现至少两次,函数返回 true.如果数组中每个元素都不相同,则返回 false. 示例 1: 输入: [1,2,3,1] 输出: true 示例 2: 输入: [1,2,3,4] 输出: false 示例 3: 输入: [1,1,1,3,3,4,3,2,4,2] 输出: true 思路: 如果一个数组中有重复元素,那么去重后的长度肯定不会等于原来的长度,这是显然的,既然python提供了set和len那么直接用就好了_(:з」∠)_…

原题地址:https://oj.leetcode.com/problems/remove-duplicates-from-sorted-list/ 题意: Given a sorted linked list, delete all duplicates such that each element appear only once. For example,Given 1->1->2, return 1->2.Given 1->1->2->3->3, retur…

原题地址:https://oj.leetcode.com/problems/max-points-on-a-line/ 题意:Given n points on a 2D plane, find the maximum number of points that lie on the same straight line. 解题思路:找到平面上在一条直线上最多的点.点在同一条直线上意味着这些点的斜率是一样的,那么可以考虑使用哈希表来解决,{斜率:[点1,点2]}这样的映射关系.这里有几个需要考虑…

原题地址:https://oj.leetcode.com/problems/median-of-two-sorted-arrays/ 题意:There are two sorted arrays A and B 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)). 解题思路:这道题要求两个已经排好…

原题地址:https://oj.leetcode.com/problems/unique-binary-search-trees-ii/ 题意:接上一题,这题要求返回的是所有符合条件的二叉查找树,而上一题要求的是符合条件的二叉查找树的棵数,我们上一题提过,求个数一般思路是动态规划,而枚举的话,我们就考虑dfs了.dfs(start, end)函数返回以start,start+1,...,end为根的二叉查找树. 代码: # Definition for a binary tree node #…

原题地址:https://oj.leetcode.com/problems/binary-tree-maximum-path-sum/ 题意: Given a binary tree, find the maximum path sum. The path may start and end at any node in the tree. For example:Given the below binary tree, 1 / \ 2 3 Return 6. 解题思路:这道题是在树中寻找一条路…

原题地址:https://oj.leetcode.com/problems/copy-list-with-random-pointer/ 题意: A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null. Return a deep copy of the list. 解题思路:这题主要是需要深…

原题地址:http://oj.leetcode.com/problems/sum-root-to-leaf-numbers/ 题意: 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-leaf path 1->2->3 which represents the number 123. Fin…

题目: 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 obstacle in the m…

这是小川的第383次更新,第412篇原创 01 看题和准备 今天介绍的是LeetCode算法题中Easy级别的第245题(顺位题号是1029).公司计划采访的人数为2N.将第i个人飞往城市A的费用是[i][0],将第i个人飞到城市B的费用是费用[i][1]. 返回将每个人带到一个城市的最低费用,这样每个城市就会有N个人到达. 例如: 输入:[[10,20],[30,200],[400,50],[30,20]] 输出:110 说明: 第一个人去城市A,费用为10. 第二个人去城市A,费用为30.…

有粉丝说我一个学算法的不去做Leetcode是不是浪费,于是今天闲来没事想尝试一下Leetcode,结果果断翻车,第一题没看懂,一直当我看到所有答案的开头都一样的时候,我意识到了我是个铁憨憨,人家是让写个函数. 两数之和 给定一个整数数组 nums 和一个目标值 target,请你在该数组中找出和为目标值的那 两个 整数,并返回他们的数组下标. 你可以假设每种输入只会对应一个答案.但是,数组中同一个元素不能使用两遍. 示例: 给定 nums = [2, 7, 11, 15], target =…

376. 摆动序列 题目 如果连续数字之间的差严格地在正数和负数之间交替,则数字序列称为 摆动序列 .第一个差(如果存在的话)可能是正数或负数.仅有一个元素或者含两个不等元素的序列也视作摆动序列. 例如, [1, 7, 4, 9, 2, 5] 是一个 摆动序列 ,因为差值 (6, -3, 5, -7, 3) 是正负交替出现的. 相反,[1, 4, 7, 2, 5] 和 [1, 7, 4, 5, 5] 不是摆动序列,第一个序列是因为它的前两个差值都是正数,第二个序列是因为它的最后一个差值为零. 子…

Length of Last Word Total Accepted: 47690 Total Submissions: 168587     Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string. If the last word does not exist, return 0. N…

Total Accepted: 3790 Total Submissions: 21072     All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T, for example: "ACGAATTCCG". When studying DNA, it is sometimes useful to identify repeated sequences within the DNA. W…

题目: Given a column title as appear in an Excel sheet, return its corresponding column number. For example: A -> 1 B -> 2 C -> 3 ... Z -> 26 AA -> 27 AB -> 28 26进制 class Solution(object): def titleToNumber(self, s): length = len(s) if len…

  #Suppose a sorted array is rotated at some pivot unknown to you beforehand. #(i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2). #You are given a target value to search. If found in the array return its index, otherwise return -1. #You may assume no…

# Definition for a binary tree node. # class TreeNode(object): # def __init__(self, x): # self.val = x # self.left = None # self.right = None class Solution(object): def rightSideView(self, root): """ :type root: TreeNode :rtype: List[int]…

# Definition for a binary tree node. # class TreeNode(object): # def __init__(self, x): # self.val = x # self.left = None # self.right = None class Solution(object): def maxDepth(self, root): """ :type root: TreeNode :rtype: int ""…

# Definition for a binary tree node. # class TreeNode(object): # def __init__(self, x): # self.val = x # self.left = None # self.right = None class Solution(object): def minDepth(self, root): """ :type root: TreeNode :rtype: int ""…

# Definition for a binary tree node. # class TreeNode(object): # def __init__(self, x): # self.val = x # self.left = None # self.right = None class Solution(object): def levelOrder(self, root): """ :type root: TreeNode :rtype: List[List[int…

class Solution(object): def removeDuplicates(self,nums): if len(nums) <= 0: return 0 j=0 for i in range(0,len(nums)): if nums[i] != nums[j]: print 'i j is ',i,j nums[i],nums[j+1] = nums[j+1],nums[i] j=j+1 return j+1…

# Definition for singly-linked list. # class ListNode(object): # def __init__(self, x): # self.val = x # self.next = None class Solution(object): def removeNthFromEnd(self, head, n): """ :type head: ListNode :type n: int :rtype: ListNode &q…

class Solution(object): def lengthOfLongestSubstring(self, s): """ :type s: str :rtype: int """ if len(s) <= 0: return 0 res = list() maxLen = 0 for i in s: if i in res: tmpLen = len(res) if tmpLen > maxLen: maxLen = tm…