2016 年 10月随笔档案 - Machelsky

277. Find the Celebrity

摘要：Suppose you are at a party with n people (labeled from 0 to n - 1) and among them, there may exist one celebrity. The definition of a celebrity is tha 阅读全文

posted @ 2016-10-13 12:08 Machelsky 阅读(190) 评论(0) 推荐(0)

187. Repeated DNA Sequences

摘要：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 阅读全文

posted @ 2016-10-13 11:40 Machelsky 阅读(198) 评论(0) 推荐(0)

172. Factorial Trailing Zeroes

摘要：Given an integer n, return the number of trailing zeroes in n!. Note: Your solution should be in logarithmic time complexity. 思路：有多少个0就是有多少个5. 零的产生就是5 阅读全文

posted @ 2016-10-13 10:31 Machelsky 阅读(128) 评论(0) 推荐(0)

48. Rotate Image

摘要：You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Follow up:Could you do this in-place? 思路：对角线对称呼唤，Y 阅读全文

posted @ 2016-10-13 10:15 Machelsky 阅读(160) 评论(0) 推荐(0)

154. Find Minimum in Rotated Sorted Array II

摘要：Follow up for "Find Minimum in Rotated Sorted Array":What if duplicates are allowed? Would this affect the run-time complexity? How and why? Suppose a 阅读全文

posted @ 2016-10-13 09:36 Machelsky 阅读(157) 评论(0) 推荐(0)

205. Isomorphic Strings

摘要：Given two strings s and t, determine if they are isomorphic. Two strings are isomorphic if the characters in s can be replaced to get t. All occurrenc 阅读全文

posted @ 2016-10-12 16:54 Machelsky 阅读(157) 评论(0) 推荐(0)

292. Nim Game

摘要：You are playing the following Nim Game with your friend: There is a heap of stones on the table, each time one of you take turns to remove 1 to 3 ston 阅读全文

posted @ 2016-10-12 16:35 Machelsky 阅读(118) 评论(0) 推荐(0)

86. Partition List

摘要：Given a linked list and a value x, partition it such that all nodes less than x come before nodes greater than or equal to x. You should preserve the 阅读全文

posted @ 2016-10-12 15:55 Machelsky 阅读(197) 评论(0) 推荐(0)

80. Remove Duplicates from Sorted Array II

摘要：Follow up for "Remove Duplicates":What if duplicates are allowed at most twice? For example,Given sorted array nums = [1,1,1,2,2,3], Your function sho 阅读全文

posted @ 2016-10-12 15:06 Machelsky 阅读(158) 评论(0) 推荐(0)

263. Ugly Number

摘要：Write a program to check whether a given number is an ugly number. Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For exa 阅读全文

posted @ 2016-10-12 14:56 Machelsky 阅读(131) 评论(0) 推荐(0)

389. Find the Difference

摘要：Given two strings s and t which consist of only lowercase letters. String t is generated by random shuffling string s and then add one more letter at 阅读全文

posted @ 2016-10-11 16:00 Machelsky 阅读(187) 评论(0) 推荐(0)

173. Binary Search Tree Iterato

摘要：Implement an iterator over a binary search tree (BST). Your iterator will be initialized with the root node of a BST. Calling next() will return the n 阅读全文

posted @ 2016-10-11 15:50 Machelsky 阅读(100) 评论(0) 推荐(0)

98. Validate Binary Search Tree

摘要：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 阅读全文

posted @ 2016-10-11 15:22 Machelsky 阅读(142) 评论(0) 推荐(0)

58. Length of Last Word

摘要：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 阅读全文

posted @ 2016-10-11 14:53 Machelsky 阅读(118) 评论(0) 推荐(0)

203. Remove Linked List Elements

摘要：Remove all elements from a linked list of integers that have value val. ExampleGiven: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6Return: 1 --> 2 -- 阅读全文

posted @ 2016-10-11 13:18 Machelsky 阅读(85) 评论(0) 推荐(0)

复习4

摘要：66. Plus One: 只需考虑数字是不是9即可，不是9，直接加1输出，是9，就继续检查更新。如果结束循环还不输出，就是全9情况，建新array输出第一位为1. 阅读全文

posted @ 2016-10-11 12:03 Machelsky 阅读(73) 评论(0) 推荐(0)

概念题

摘要：1. HashMap 和 HashTable 转：http://www.cnblogs.com/devinzhang/archive/2012/01/13/2321481.html 阅读全文

posted @ 2016-10-11 08:24 Machelsky 阅读(96) 评论(0) 推荐(0)

73. Set Matrix Zeroes

摘要：Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place. 122/145 思路：遍历整个matrix，找到element是0的时候，记录对应的row和column。有两个阅读全文

posted @ 2016-10-10 13:04 Machelsky 阅读(93) 评论(0) 推荐(0)

268. Missing Number

摘要：Given an array containing n distinct numbers taken from 0, 1, 2, ..., n, find the one that is missing from the array. For example,Given nums = [0, 1, 阅读全文

posted @ 2016-10-10 12:35 Machelsky 阅读(121) 评论(0) 推荐(0)

200. Number of Islands

摘要：Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacen 阅读全文

posted @ 2016-10-10 07:35 Machelsky 阅读(142) 评论(0) 推荐(0)

28. Implement strStr()

摘要：Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. 思路：对应检查char是否一样，不一样直接跳出检阅读全文

posted @ 2016-10-10 07:19 Machelsky 阅读(315) 评论(0) 推荐(0)

345. Reverse Vowels of a String

摘要：Write a function that takes a string as input and reverse only the vowels of a string. Example 1:Given s = "hello", return "holle". Example 2:Given s 阅读全文

posted @ 2016-10-10 07:04 Machelsky 阅读(146) 评论(0) 推荐(0)

复习3

摘要：160. Intersection of Two Linked Lists 1.各自扫一遍list找到第一个相同节点 2.各自扫一遍，记录长度。将长的缩小到跟短的一样，相同长度的情况下找同节点。 136. Single Number: A^0=A A^A=0 最后留下A 阅读全文

posted @ 2016-10-10 06:55 Machelsky 阅读(85) 评论(0) 推荐(0)

125. Valid Palindrome

摘要：Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. For example,"A man, a plan, a canal: Pan 阅读全文

posted @ 2016-10-10 06:24 Machelsky 阅读(108) 评论(0) 推荐(0)

3. Longest Substring Without Repeating Characters

摘要：Given a string, find the length of the longest substring without repeating characters. Examples: Given "abcabcbb", the answer is "abc", which the leng 阅读全文

posted @ 2016-10-10 06:02 Machelsky 阅读(114) 评论(0) 推荐(0)

387. First Unique Character in a String

摘要：Given a string, find the first non-repeating character in it and return it's index. If it doesn't exist, return -1. Examples: 阅读全文

posted @ 2016-10-10 05:35 Machelsky 阅读(138) 评论(0) 推荐(0)

145. Binary Tree Postorder Traversal

摘要：Given a binary tree, return the postorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, return [3,2,1]. 思路：后序遍历阅读全文

posted @ 2016-10-09 10:31 Machelsky 阅读(134) 评论(0) 推荐(0)

94. Binary Tree Inorder Traversal

摘要：Given a binary tree, return the inorder traversal of its nodes' values. For example:Given binary tree [1,null,2,3], return [1,3,2]. 思路：中序遍历。阅读全文

posted @ 2016-10-09 10:26 Machelsky 阅读(109) 评论(0) 推荐(0)

144. Binary Tree Preorder Traversal

摘要：Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, return [1,2,3]. Note: Recursive solu 阅读全文

posted @ 2016-10-09 10:17 Machelsky 阅读(104) 评论(0) 推荐(0)

165. Compare Version Numbers

摘要：Compare two version numbers version1 and version2.If version1 > version2 return 1, if version1 < version2 return -1, otherwise return 0. You may assum 阅读全文

posted @ 2016-10-09 10:01 Machelsky 阅读(174) 评论(0) 推荐(0)

60. Permutation Sequence

摘要：The set [1,2,3,…,n] contains a total of n! unique permutations. By listing and labeling all of the permutations in order,We get the following sequence 阅读全文

posted @ 2016-10-09 06:05 Machelsky 阅读(101) 评论(0) 推荐(0)

374. Guess Number Higher or Lower

摘要：We are playing the Guess Game. The game is as follows: I pick a number from 1 to n. You have to guess which number I picked. Every time you guess wron 阅读全文

posted @ 2016-10-09 04:35 Machelsky 阅读(162) 评论(0) 推荐(0)

109. Convert Sorted List to Binary Search Tree

摘要：Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST. Given a singly linked list where element 阅读全文

posted @ 2016-10-09 03:48 Machelsky 阅读(139) 评论(0) 推荐(0)

35. Search Insert Position

摘要：Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in or 阅读全文

posted @ 2016-10-09 03:36 Machelsky 阅读(121) 评论(0) 推荐(0)

16. 3Sum Closest

摘要：Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. 阅读全文

posted @ 2016-10-09 03:26 Machelsky 阅读(142) 评论(0) 推荐(0)

61. Rotate List

摘要：Given a list, rotate the list to the right by k places, where k is non-negative. For example:Given 1->2->3->4->5->NULL and k = 2,return 4->5->1->2->3- 阅读全文

posted @ 2016-10-09 03:02 Machelsky 阅读(130) 评论(0) 推荐(0)

复习2

摘要：190. Reverse Bits:原数向右移动，如果bit是1，就给结果在相应的位置加上1. 46. Permutations:最适合这道题的dfs搜索顺序是把加一个限制条件：搜索过的数字跳过。脑子里面有个tree的模型然后去想应该搜索的顺序和条件。 100. Same Tree: 递归：检查是不阅读全文

posted @ 2016-10-09 02:34 Machelsky 阅读(84) 评论(0) 推荐(0)

89. Gray Code

摘要：The gray code is a binary numeral system where two successive values differ in only one bit. Given a non-negative integer n representing the total num 阅读全文

posted @ 2016-10-09 02:25 Machelsky 阅读(140) 评论(0) 推荐(0)

204. Count Primes

摘要：Description: Count the number of prime numbers less than a non-negative number, n. 刷了一周的python, 希望明天把blackjack和最后的游戏做出来。思路：比较巧妙，用inner loop从头开始mark不阅读全文

posted @ 2016-10-08 17:14 Machelsky 阅读(94) 评论(0) 推荐(0)

复习1

摘要：1. Two sum: map解决，扫一遍记录位置为key，值为剩下值。 2. Add Two Numbers: 链表扫一遍， dummy node接算出来的node，跑完一个跑另一个，最后接上多出的node1 136. Single Number: 可以用map也可以用bit manipulati 阅读全文

posted @ 2016-10-08 16:42 Machelsky 阅读(89) 评论(0) 推荐(0)

179. Largest Number

摘要：Given a list of non negative integers, arrange them such that they form the largest number. For example, given [3, 30, 34, 5, 9], the largest formed n 阅读全文

posted @ 2016-10-08 15:23 Machelsky 阅读(108) 评论(0) 推荐(0)

147. Insertion Sort List

摘要：Sort a linked list using insertion sort. 思路：插入排序，就是把node插入到左边的链表中。用一个dummynode来构造左边的链表。要是比最左边的数还小，就插到最左边也就是dummy.next。如果不是，则linear search左边的链表插入。阅读全文

posted @ 2016-10-08 15:13 Machelsky 阅读(118) 评论(0) 推荐(0)

24. Swap Nodes in Pairs

摘要：Given a linked list, swap every two adjacent nodes and return its head. For example,Given 1->2->3->4, you should return the list as 2->1->4->3. Your a 阅读全文

posted @ 2016-10-08 14:39 Machelsky 阅读(117) 评论(0) 推荐(0)

79. Word Search

摘要：Given a 2D board and a word, find if the word exists in the grid. The word can be constructed from letters of sequentially adjacent cell, where "adjac 阅读全文

posted @ 2016-10-08 14:26 Machelsky 阅读(174) 评论(0) 推荐(0)

69. Sqrt(x)

摘要：Implement int sqrt(int x). 二分法，找中值。注意不能用low<high来判断。举例：sqrt(5)，low<high的话一直在2的右边搜索，最后low=3 high=3是不正确的，要再进入循环去得到最后的结果。阅读全文

posted @ 2016-10-08 14:04 Machelsky 阅读(124) 评论(0) 推荐(0)

334. Increasing Triplet Subsequence

摘要：Given an unsorted array return whether an increasing subsequence of length 3 exists or not in the array. Formally the function should: Your algorithm 阅读全文

posted @ 2016-10-04 16:26 Machelsky 阅读(96) 评论(0) 推荐(0)

328. Odd Even Linked List

摘要：Given a singly linked list, group all odd nodes together followed by the even nodes. Please note here we are talking about the node number and not the 阅读全文

posted @ 2016-10-04 16:00 Machelsky 阅读(126) 评论(0) 推荐(0)