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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
273
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
167
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->1 Output: 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
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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
391
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 = 3 Output: [5,6,7,1,2,3,4] Explanation: rotat...
2019-03-30 23:28:12
202
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: 5 Output: 1 Explanation: 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
225
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
238
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
288
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
211
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
291
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
244
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
219
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
496
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
256
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
285
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
263
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
277
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
278
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
377
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
359
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
320
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
363
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