12 2014 档案

Leetcode:Convert Sorted Array to Binary Search Tree
摘要：Given an array where elements are sorted in ascending order, convert it to a height balanced BST.分析：对于BST，左右子树的高度差小于等于1，则在由sorted array构建BST时把数组中间元素作为... 阅读全文

posted @ 2014-12-31 15:03 Ryan-Xing 阅读(115) 评论(0) 推荐(0)

Leetcode:Binary Tree Level Order Traversal II
摘要：Given a binary tree, return thebottom-up level ordertraversal of its nodes' values. (ie, from left to right, level by level from leaf to root).For exa... 阅读全文

posted @ 2014-12-29 12:53 Ryan-Xing 阅读(154) 评论(0) 推荐(0)

Leetcode:Binary Tree Level Order Traversal
摘要：Given a binary tree, return thelevel ordertraversal of its nodes' values. (ie, from left to right, level by level).For example:Given binary tree{3,9,2... 阅读全文

posted @ 2014-12-29 12:36 Ryan-Xing 阅读(128) 评论(0) 推荐(0)

Leetcode:Balanced Binary Tree
摘要：Given a binary tree, determine if it is height-balanced.For this problem, a height-balanced binary tree is defined as a binary tree in which the depth... 阅读全文

posted @ 2014-12-29 12:24 Ryan-Xing 阅读(110) 评论(0) 推荐(0)

Binary Tree Maximum Path Sum
摘要：class Solution {public: int maxPathSum(TreeNode *root) { if(root == NULL) return 0; int max_sum = INT_MIN; unordered_map node_... 阅读全文

posted @ 2014-12-19 21:17 Ryan-Xing 阅读(113) 评论(0) 推荐(0)

Quant面试准备5本书
摘要：Heard on The Street: Quantitative Questions from Wall Street Job Interviews- Timothy Falcon CrackFrequently Asked Questions in Quantitative Finance- P... 阅读全文

posted @ 2014-12-19 21:15 Ryan-Xing 阅读(1853) 评论(0) 推荐(1)

Leetcode: Evaluate Reverse Polish Notation
摘要：Evaluate the value of an arithmetic expression inReverse Polish Notation.Valid operators are+,-,*,/. Each operand may be an integer or another express... 阅读全文

posted @ 2014-12-15 21:30 Ryan-Xing 阅读(126) 评论(0) 推荐(0)

Leetcode: Largest Rectangle in Histogram
摘要：Givennnon-negative integers representing the histogram's bar height where the width of each bar is 1, find the area of largest rectangle in the histog... 阅读全文

posted @ 2014-12-12 20:34 Ryan-Xing 阅读(136) 评论(0) 推荐(0)

Leetcode: Valid Number
摘要：Validate if a given string is numeric.Some examples:"0"=>true" 0.1 "=>true"abc"=>false"1 a"=>false"2e10"=>trueNote:It is intended for the problem stat... 阅读全文

posted @ 2014-12-12 12:54 Ryan-Xing 阅读(240) 评论(0) 推荐(0)

Leetcode: Anagrams
摘要：Given an array of strings, return all groups of strings that are anagrams.Note: All inputs will be in lower-case.分析：此题的题意不是很明确，意思重新表述应该是一组string里面，有几个... 阅读全文

posted @ 2014-12-10 20:56 Ryan-Xing 阅读(155) 评论(0) 推荐(0)

Leetcode: Distinct Subsequences
摘要：Given a stringSand a stringT, count the number of distinct subsequences ofTinS.A subsequence of a string is a new string which is formed from the orig... 阅读全文

posted @ 2014-12-10 14:01 Ryan-Xing 阅读(129) 评论(0) 推荐(0)

Python下载Yahoo!Finance数据
摘要：Python下载Yahoo!Finance数据的三种工具：（1）yahoo-finance package.（2）ystockquote.（3）pandas. 阅读全文

posted @ 2014-12-09 22:01 Ryan-Xing 阅读(1779) 评论(0) 推荐(0)

Leetcode: Integer to Roman
摘要：Given an integer, convert it to a roman numeral.Input is guaranteed to be within the range from 1 to 3999.分析：这道题参考leetcode.pdf的解法，代码简洁，处理的巧妙。值得借鉴的几点如下... 阅读全文

posted @ 2014-12-09 20:26 Ryan-Xing 阅读(92) 评论(0) 推荐(0)

Leetcode: Interleaving String
摘要：Givens1,s2,s3, find whethers3is formed by the interleaving ofs1ands2.For example,Given:s1="aabcc",s2="dbbca",Whens3="aadbbcbcac", return true.Whens3="... 阅读全文

posted @ 2014-12-09 19:46 Ryan-Xing 阅读(131) 评论(0) 推荐(0)

Leetcode: Length of Last Word
摘要：Given a stringsconsists of upper/lower-case alphabets and empty space characters' ', return the length of last word in the string.If the last word doe... 阅读全文

posted @ 2014-12-09 13:35 Ryan-Xing 阅读(89) 评论(0) 推荐(0)

Leetcode: Longest Common Prefix
摘要：Write a function to find the longest common prefix string amongst an array of strings.分析：这道题没什么好方法，暴力搜索比较即可，在用C++实现时有一个小trick就是"Ifposis equal to thest... 阅读全文

posted @ 2014-12-09 12:47 Ryan-Xing 阅读(91) 评论(0) 推荐(0)

Leetcode: Longest Palindromic Substring
摘要：Given a stringS, find the longest palindromic substring inS. You may assume that the maximum length ofSis 1000, and there exists one unique longest pa... 阅读全文

posted @ 2014-12-09 12:07 Ryan-Xing 阅读(184) 评论(0) 推荐(0)

Leetcode: Longest Substring Without Repeating Characters
摘要：Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters fo... 阅读全文

posted @ 2014-12-08 19:39 Ryan-Xing 阅读(132) 评论(0) 推荐(0)

Leetcode: Binary Tree Maximum Path Sum
摘要：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 ... 阅读全文

posted @ 2014-12-08 12:46 Ryan-Xing 阅读(176) 评论(0) 推荐(0)

Leetcode: Edit Distance
摘要：Given two wordsword1andword2, find the minimum number of steps required to convertword1toword2. (each operation is counted as 1 step.)You have the fol... 阅读全文

posted @ 2014-12-07 16:18 Ryan-Xing 阅读(131) 评论(0) 推荐(0)

Leetcode: Sort Colors
摘要：Given an array withnobjects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order red, wh... 阅读全文

posted @ 2014-12-07 15:36 Ryan-Xing 阅读(165) 评论(0) 推荐(0)

Leetcode: 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 "adjace... 阅读全文

posted @ 2014-12-07 00:47 Ryan-Xing 阅读(116) 评论(0) 推荐(0)

Leetcode: Intersection of Two Linked Lists
摘要：Write a program to find the node at which the intersection of two singly linked lists begins.For example, the following two linked lists:A: a... 阅读全文

posted @ 2014-12-06 20:22 Ryan-Xing 阅读(146) 评论(0) 推荐(0)

Leetcode: Generate Parentheses
摘要：Givennpairs of parentheses, write a function to generate all combinations of well-formed parentheses.For example, givenn= 3, a solution set is:"((()))... 阅读全文

posted @ 2014-12-05 21:16 Ryan-Xing 阅读(186) 评论(0) 推荐(0)

Leetcode: Maximum Depth of Binary Tree
摘要：Given a binary tree, find its maximum depth.The maximum depth is the number of nodes along the longest path from the root node down to the farthest le... 阅读全文

posted @ 2014-12-05 19:55 Ryan-Xing 阅读(114) 评论(0) 推荐(0)

Leetcode: Pascal's Triangle II
摘要：Given an indexk, return thekthrow of the Pascal's triangle.For example, givenk= 3,Return[1,3,3,1].Note:Could you optimize your algorithm to use onlyO(... 阅读全文

posted @ 2014-12-05 17:07 Ryan-Xing 阅读(145) 评论(0) 推荐(0)

Leetcode: 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.分析：该题是经典的串匹配，我们可以用KMP来解，时间... 阅读全文

posted @ 2014-12-05 15:40 Ryan-Xing 阅读(213) 评论(0) 推荐(0)

Leetcode: Binary Tree Postorder Traversal
摘要：Given a binary tree, return thepostordertraversal of its nodes' values.For example:Given binary tree{1,#,2,3}, 1 \ 2 / 3return[3,2,1].No... 阅读全文

posted @ 2014-12-04 20:51 Ryan-Xing 阅读(131) 评论(0) 推荐(0)

Leetcode: Binary Tree Preorder Traversal
摘要：Given a binary tree, return thepreordertraversal of its nodes' values.For example:Given binary tree{1,#,2,3}, 1 \ 2 / 3return[1,2,3].Not... 阅读全文

posted @ 2014-12-04 20:20 Ryan-Xing 阅读(200) 评论(0) 推荐(0)

Leetcode: Binary Tree Inorder Traversal
摘要：Given a binary tree, return theinordertraversal of its nodes' values.For example:Given binary tree{1,#,2,3}, 1 \ 2 / 3return[1,3,2].Note... 阅读全文

posted @ 2014-12-04 20:07 Ryan-Xing 阅读(214) 评论(0) 推荐(0)

Leetcode: Longest Valid Parentheses
摘要：Given a string containing just the characters'('and')', find the length of the longest valid (well-formed) parentheses substring.For"(()", the longest... 阅读全文

posted @ 2014-12-04 19:15 Ryan-Xing 阅读(175) 评论(0) 推荐(0)

Leetcode: Multiply Strings
摘要：Given two numbers represented as strings, return multiplication of the numbers as a string.Note: The numbers can be arbitrarily large and are non-nega... 阅读全文

posted @ 2014-12-04 15:01 Ryan-Xing 阅读(126) 评论(0) 推荐(0)

Leetcode: Climbing Stairs
摘要：You are climbing a stair case. It takesnsteps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb... 阅读全文

posted @ 2014-12-03 23:59 Ryan-Xing 阅读(111) 评论(0) 推荐(0)

Leetcode: Regular Expression Matching
摘要：Implement regular expression matching with support for'.'and'*'.'.' Matches any single character.'*' Matches zero or more of the preceding element.The... 阅读全文

posted @ 2014-12-03 22:14 Ryan-Xing 阅读(157) 评论(0) 推荐(0)

Leetcode: Restore IP Addresses
摘要：Given a string containing only digits, restore it by returning all possible valid IP address combinations.For example:Given"25525511135",return["255.2... 阅读全文

posted @ 2014-12-02 21:45 Ryan-Xing 阅读(124) 评论(0) 推荐(0)

Leetcode: Roman to Integer
摘要：Given a roman numeral, convert it to an integer.Input is guaranteed to be within the range from 1 to 3999.分析：首先我们熟悉下Roman数字组成规则：罗马数字一共有7个符号，'I':1, 'V'... 阅读全文

posted @ 2014-12-02 20:40 Ryan-Xing 阅读(141) 评论(0) 推荐(0)

Leetcode: Scramble String
摘要：Given a strings1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively.Below is one possible representation... 阅读全文

posted @ 2014-12-02 19:39 Ryan-Xing 阅读(176) 评论(0) 推荐(0)

Leetcode: Simplify Path
摘要：Given an absolute path for a file (Unix-style), simplify it.For example,path="/home/", =>"/home"path="/a/./b/../../c/", =>"/c"click to show corner cas... 阅读全文

posted @ 2014-12-02 17:20 Ryan-Xing 阅读(162) 评论(0) 推荐(0)

Leetcode: String to Integer (atoi)
摘要：Implementatoito convert a string to an integer.Hint:Carefully consider all possible input cases. If you want a challenge, please do not see below and ... 阅读全文

posted @ 2014-12-02 15:29 Ryan-Xing 阅读(273) 评论(0) 推荐(0)