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RSS订阅原创 [LeetCode刷题日记(Day25)]:Course Schedule
Problem 207. Course Schedule题目描述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 cou...
2019-04-11 12:55:55
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原创 [LeetCode刷题日记(Day24)]:Evaluate Reverse Polish Notation
Problem 150. Evaluate Reverse Polish Notation题目描述Evaluate the value of an arithmetic expression in Reverse Polish Notation.Valid operators are +, -, *, /. Each operand may be an integer or anothe...
2019-04-05 17:47:30
173
原创 [LeetCode刷题日记(Day24)]:Word Break
Problem 139. Word Break题目描述Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, determine if s can be segmented into a space-separated sequence of one or more...
2019-04-05 16:59:09
106
原创 [LeetCode刷题日记(Day24)]:Gas Station
Problem 134. Gas Station题目描述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 it costs cost[i] of gas t...
2019-04-05 16:01:31
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原创 [LeetCode刷题日记(Day24)]:Palindrome Partitioning
Problem 131. Palindrome Partitioning题目描述Given a string s, partition s such that every substring of the partition is a palindrome.Return all possible palindrome partitioning of s.Example:Input: ...
2019-04-05 15:26:48
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原创 [LeetCode刷题日记(Day23)]:Binary Tree Level Order Traversal
Problem 102. Binary Tree Level Order Traversal题目描述Given a binary tree, return the level order traversal of its nodes’ values. (ie, from left to right, level by level).For example:Given binary tr...
2019-04-04 13:48:39
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原创 [LeetCode刷题日记(Day23)]:Validate Binary Search Tree
Problem 98. Validate Binary Search Tree题目描述Given a binary tree, determine if it is a valid binary search tree (BST).Assume a BST is defined as follows:The left subtree of a node contains only n...
2019-04-04 13:04:54
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原创 LeetCode刷题日记（Day22）
Problem 242. Valid Anagram题目描述Given two strings s and t , write a function to determine if t is an anagram of s.Example：Input: s = "anagram", t = "nagaram"Output: true解题思路要判断一个字符串是否由另一个字符串...
2019-04-03 13:10:46
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原创 LeetCode刷题日记（Day21）
Problem 234. Palindrome Linked List题目描述Given a singly linked list, determine if it is a palindrome.Example：Input: 1->2->2->1Output: true解题思路要判断一个链表是否是回文链表，且要求时间复杂度和空间复杂度分别为 O(n) 和...
2019-04-02 15:22:29
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原创 LeetCode刷题日记（Day20）
Problem 202. Happy Number题目描述Write an algorithm to determine if a number is “happy”.A happy number is a number defined by the following process: Starting with any positive integer, replace the nu...
2019-04-01 20:45:16
143
原创 LeetCode刷题日记（Day19）
Problem 198. House Robber题目描述You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing ea...
2019-03-31 23:41:06
231
原创 LeetCode刷题日记（Day18）
Problem 189. Rotate Array题目描述Given an array, rotate the array to the right by k steps, where k is non-negative.Example：Input: [1,2,3,4,5,6,7] and k = 3Output: [5,6,7,1,2,3,4]Explanation:rotat...
2019-03-30 23:28:12
144
原创 LeetCode刷题日记（Day17）
Problem 172. Factorial Trailing Zeroes题目描述Given an integer n, return the number of trailing zeroes in n!.Example：Input: 5Output: 1Explanation: 5! = 120, one trailing zero.解题思路本题要求的是 n 的阶乘...
2019-03-26 18:47:49
151
原创 LeetCode刷题日记（Day16）
Problem 136. Single Number题目描述Given a non-empty array of integers, every element appears twice except for one. Find that single one.Note:Your algorithm should have a linear runtime complexity. C...
2019-03-26 13:01:28
186
原创 LeetCode刷题日记（Day15）
Problem 118. Pascal’s Triangle题目描述Given a non-negative integer numRows, generate the first numRows of Pascal’s triangle.In Pascal’s triangle, each number is the sum of the two numbers directly ab...
2019-03-25 21:07:08
170
原创 LeetCode刷题日记（Day14）
Problem 105. Construct Binary Tree from Preorder and Inorder Traversal题目描述Given preorder and inorder traversal of a tree, construct the binary tree.Note:You may assume that duplicates do not exi...
2019-03-24 11:39:41
138
原创 LeetCode刷题日记（Day13）
Problem 88. Merge Sorted Array题目描述Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.Note:The number of elements initialized in nums1 and nums2 are m an...
2019-03-24 09:09:59
169
原创 LeetCode刷题日记（Day12）
Problem 78. Subsets题目描述Given a set of distinct integers, nums, return all possible subsets (the power set).Note: The solution set must not contain duplicate subsets.Example:Input: nums = [1,2,3...
2019-03-18 21:23:42
195
原创 LeetCode刷题日记（Day11）
Problem 73. Set Matrix Zeroes题目描述Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in-place.Example:Input: [ [0,1,2,0], [3,4,5,2], [1,3,1,5]]Output: [...
2019-03-16 16:48:49
172
原创 LeetCode刷题日记（Day10）
Problem 56. Merge Intervals题目描述Given a collection of intervals, merge all overlapping intervals.Example:Input: [[1,3],[2,6],[8,10],[15,18]]Output: [[1,6],[8,10],[15,18]]Explanation: Since inte...
2019-03-15 20:40:34
351
原创 LeetCode刷题日记（Day9）
Problem 49. Group Anagrams题目描述Given an array of strings, group anagrams together.Example:Input: ["eat", "tea", "tan",
2019-03-15 15:05:45
194
原创 LeetCode刷题日记（Day8）
Problem 33. Search in Rotated Sorted Array题目描述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 become [4,5,6,7,0,1,2]).Y...
2019-03-14 13:15:13
190
原创 LeetCode刷题日记（Day7）
Problem 21. Merge Two Sorted Lists题目描述Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.解题思路此题较简单，创建一...
2019-03-13 13:44:00
211
原创 LeetCode刷题日记（Day6）
Problem 19. Remove Nth Node From End of List题目描述Given a linked list, remove the n-th node from the end of list and return its head.解题思路要删除链表中倒数第 n 个节点，可以采取双指针的办法，一个快指针 cur，一个慢指针 pre，其中快指针 cur ...
2019-03-12 17:44:00
176
原创 LeetCode刷题日记（Day5）
Problem 14. Longest Common Prefix题目描述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 “”.解题思路本题采用的是迭代...
2019-03-11 17:07:49
229
原创 LeetCode刷题日记（Day4）
Problem 8. String to Integer (atoi)题目描述Implement atoi which converts a string to an integer.The function first discards as many whitespace characters as necessary until the first non-whitespace c...
2019-03-09 13:33:29
255
原创 LeetCode刷题日记（Day3）
Problem 5. Longest Palindromic Substring题目描述Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000.解题思路：回文子串，即正序和倒序输出结果都一样的字符串。例如字符串...
2019-03-08 11:10:04
245
原创 LeetCode刷题日记（Day2）
Problem 3. Longest Substring Without Repeating Characters 题目描述Given a string, find the length of the longest substring without repeating characters.解题思路：定义int变量len，初始化为0，表示最长子串；int变量left表...
2019-03-07 22:14:36
268
原创 LeetCode刷题日记（Day1）
Problem 1. Two Sum 解题思路：创建map<int, int>变量m，对传入的nums进行遍历，并将遍历过的nums[i]存入到m当中。创建变量temp，对nums再进行一次遍历，将target - nums[i]赋值给temp，并判断temp是否在m中已有。如果有，则找到解。时间复杂度分析：由于对nums进行一次遍历的代价为O(n)，且每个num...
2019-03-06 21:58:42
285
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