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原创九章算法强化 Lecture 5 DP上滚动数组划分型博弈型区间型

滚动数组 110 确定状态研究最优策略的最后一步转化为子问题转移方程根据子问题定义直接得到初始条件和边界情况仔细，考虑周全计算顺序利用之前的计算结果划分型动态规划 512 676 博弈动态规划 395 区间型动态规划求一段区间的最大最小值 168 ...

2020-03-02 05:16:43 246

原创九章算法强化 Lecture 4 扫描线二分法双端队列

扫描线例题 LintCode 391. Number of Airplanes in the Sky Given an list interval, which are taking off and landing time of the flight. How many airplanes are there at most at the same time in the sky? Examp...

2020-03-02 02:28:52 558

原创 Java 数据类型转换以及 Arrays Collections

array 和 ArrayList 转换 array -> ArrayList 把 array 中的每个元素加到 ArrayList 中 List staffsList = new ArrayList<String>(); for(String temp: staffs) { staffsList.add(temp); } ArrayList -> array...

2020-01-13 12:31:46 234

原创 LeetCode BinarySearch 69. Sqrt(x)

69. Sqrt(x) Implement int sqrt(int x). Compute and return the square root of x, where x is guaranteed to be a non-negative integer. Since the return type is an integer, the decimal digits are truncate...

2019-12-24 09:55:20 165

原创 LeetCode BinarySearch 852. Peak Index in a Mountain Array 1095. Find in Mountain Array

852. Peak Index in a Mountain Array Let’s call an array A a mountain if the following properties hold: A.length >= 3 There exists some 0 < i < A.length - 1 such that A[0]<A[1]<...A[i−1...

2019-12-24 06:18:46 177

原创 LeetCode BinarySearch 162. Find Peak Element

162. Find Peak Element A peak element is an element that is greater than its neighbors. Given an input array nums, where nums[i] ≠ nums[i+1], find a peak element and return its index. The array may co...

2019-12-24 05:38:42 169

原创 LeetCode BinarySearch 240. Search a 2D Matrix II

240. Search a 2D Matrix II Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties: Integers in each row are sorted in ascending from left t...

2019-12-24 05:21:05 150

原创 LeetCode BinarySearch 74 Search a 2D Matrix

74. Search a 2D Matrix Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties: Integers in each row are sorted from left to right. The firs...

2019-12-24 00:52:08 114

原创 Leetcode BinarySearch 302 Smallest Rectangle Enclosing Black Pixels

302. Smallest Rectangle Enclosing Black Pixels An image is represented by a binary matrix with 0 as a white pixel and 1 as a black pixel. The black pixels are connected, i.e., there is only one black ...

2019-12-23 13:12:58 261

原创 LeetCode BinarySearch 33 & 81 Search in Rotated Sorted Array I II

33. Search in Rotated Sorted Array 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]). You are given a ...

2019-12-23 13:10:56 176

原创 Leetcode BinarySearch 153 154 Find Minimum in Rotated Sorted Array l & ll

153. Find Minimum in Rotated Sorted Array 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]). Find th...

2019-12-22 09:14:01 115

原创 LeetCode BinarySearch 702 Search in a Sorted Array of Unknown Size

702. Search in a Sorted Array of Unknown Size Given an integer array sorted in ascending order, write a function to search target in nums. If target exists, then return its index, otherwise return -1...

2019-12-22 05:14:22 222

原创 LeetCode BinarySearch 278 first bad version

Leetcode 278 first bad version You are a product manager and currently leading a team to develop a new product. Unfortunately, the latest version of your product fails the quality check. Since each ve...

2019-12-22 04:28:29 136

原创 LeetCode BinarySearch 34 Find First and Last Position of Element in Sorted Array

34. Find First and Last Position of Element in Sorted Array Given an array of integers nums sorted in ascending order, find the starting and ending position of a given target value. Your algorithm’s r...

2019-12-22 03:48:29 116

原创 LeetCode Backtracking 46 Permutations 47 Permutationsll

46. Permutations Given a collection of distinct integers, return all possible permutations. Example: Input: [1,2,3] Output: [ [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], [3,2,1] ] solution 由于是要得到所有的排...

2019-12-22 00:53:46 162

原创 LeetCode DFS 78 Subsets 90 Subsets ll

Subsets 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] Output: [ [3], ...

2019-12-21 13:24:29 153

原创 LeetCodeBasics .length() .length .size() .add() .put()

1 .length() String, 2 .length int[], char[], 3 .size() ArratList, HashMap 4 .add() HashSet, ArratList, 5 .put() HashMap,

2019-12-21 12:18:06 140

原创 LeetCode Array 289 Game of Life

289. Game of Life (Medium) According to the Wikipedia’s article: “The Game of Life, also known simply as Life, is a cellular automaton devised by the British mathematician John Horton Conway in 1970.”...

2019-12-21 09:19:26 166

原创 LeetCode String 32 Longest Valid Parentheses

32. Longest Valid Parentheses Given a string containing just the characters ‘(’ and ‘)’, find the length of the longest valid (well-formed) parentheses substring. Example 1: Input: “(()” Output: 2 Exp...

2019-12-20 11:08:00 225

原创 LeetCode String 22 Generate Parentheses

22. Generate Parentheses Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses. For example, given n = 3, a solution set is: [ “((()))”, “(()())”, “(()...

2019-12-20 01:13:19 146

原创 LeetCode String 20 Valid Parentheses

20. Valid Parentheses Given a string containing just the characters ‘(’, ‘)’, ‘{’, ‘}’, ‘[’ and ‘]’, determine if the input string is valid. An input string is valid if: Open brackets must be closed b...

2019-12-19 14:31:16 108

原创 LeetCode String 336 Palindrome Pairs

336. Palindrome Pairs Given a list of unique words, find all pairs of distinct indices (i, j) in the given list, so that the concatenation of the two words, i.e. words[i] + words[j] is a palindrome. E...

2019-12-19 14:05:45 189

原创 LeetCode String 5 Longest Palindromic Substring

5. Longest Palindromic Substring Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000. Example 1: Input: “babad” Output: “bab” Note: “aba”...

2019-12-19 10:41:23 154

原创 LeetCode String 125 Valid Palindrome

125. Valid Palindrome Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. Note: For the purpose of this problem, we define empty string as val...

2019-12-19 08:46:24 122

原创 LeetCode String 76 Minimum Window Substring

76. Minimum Window Substring Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n). Example: Input: S = “ADOBECODEBANC”, T = “ABC”...

2019-12-19 07:24:51 117

原创 LeetCode String 65 Valid Number

65. Valid Number Validate if a given string can be interpreted as a decimal number. Some examples: “0” => true " 0.1 " => true “abc” => false “1 a” => false “2e10” => true " -90e3 " =...

2019-12-19 05:34:12 125

原创 LeetCode String 68 Text Justification

68. Text Justification Given an array of words and a width maxWidth, format the text such that each line has exactly maxWidth characters and is fully (left and right) justified. You should pack your w...

2019-12-19 04:41:33 113

原创 LeetCode String 157 158 Read N Characters Given Read4 I and II

157. Read N Characters Given Read4 Given a file and assume that you can only read the file using a given method read4, implement a method to read n characters. Method read4: The API read4 reads 4 cons...

2019-12-19 01:17:16 183

原创 LeetCode String 273 Integer to English Words

273. Integer to English Words Convert a non-negative integer to its english words representation. Given input is guaranteed to be less than 2312^{31}231 - 1. Example 1: Input: 123 Output: “One Hundred...

2019-12-18 09:18:35 141

原创 LeetCode String 12 Integer to Roman

12. Integer to Roman Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. Symbol Value I 1 V 5 X 10 L 50 C ...

2019-12-18 08:57:22 120

原创 LeetCode String 13 Roman to Integer

13. Roman to Integer Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. Symbol Value I 1 V 5 X 10 L 50 C ...

2019-12-18 00:18:54 151

原创 LeetCode String 171 Excel Sheet Column Number

171. Excel Sheet Column Number 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 -> ...

2019-12-17 23:58:23 128

原创 LeetCode String 168 Excel Sheet Column Title

168. Excel Sheet Column Title Given a positive integer, return its corresponding column title as appear in an Excel sheet. For example: 1 -> A 2 -> B 3 -> C … 26 -> Z 27 -> AA 28 -> ...

2019-12-06 04:22:52 102

原创 LeetCode String 316 Remove Duplicate Letters

316. Remove Duplicate Letters Given a string which contains only lowercase letters, remove duplicate letters so that every letter appears once and only once. You must make sure your result is the smal...

2019-12-06 03:52:26 148

原创 LeetCode String 38 Count and Say

38. Count and Say The count-and-say sequence is the sequence of integers with the first five terms as following: 1 11 21 1211 111221 1 is read off as “one 1” or 11. 11 is read off as ...

2019-12-01 12:46:49 130

原创 LeetCode String 161 One Edit Distance

161. One Edit Distance Given two strings s and t, determine if they are both one edit distance apart. Note: There are 3 possiblities to satisify one edit distance apart: Insert a character into s to g...

2019-12-01 11:32:43 142

原创 LeetCode String 6 ZigZag Conversion

6. ZigZag Conversion The string “PAYPALISHIRING” is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility) And t...

2019-12-01 06:11:12 97

原创 LeetCode String 179 Largest Number

179. Largest Number Given a list of non negative integers, arrange them such that they form the largest number. Example 1: Input: [10,2] Output: “210” Example 2: Input: [3,30,34,5,9] Output: “9534330”...

2019-12-01 04:16:31 138

原创 LeetCode String 87 Scramble String

87. Scramble String Given a string s1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively. Below is one possible representation of s1 = “great”: To scramb...

2019-12-01 01:43:13 144

原创 LeetCode String 49 Group Anagrams

49. Group Anagrams Given an array of strings, group anagrams together. Example: Input: [“eat”, “tea”, “tan”, “ate”, “nat”, “bat”], Output: [ [“ate”,“eat”,“tea”], [“nat”,“tan”], [“bat”] ] Note: All inp...

2019-11-30 02:55:50 133

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