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转载 LeetCode Single Number I & II 都符合两个问题额外要求的通用解法与思考过程

Single NumberGiven an array of integers, every element appears twice except for one. Find that single one.Note:Your algorithm should have a linear runtime complexity. Could you implement it

2014-10-06 12:34:50 622

原创 Linked List Cycle

Given a linked list, determine if it has a cycle in it.Follow up:Can you solve it without using extra space?

2014-09-29 14:49:40 575

原创 [leetcode ] gray code

class Solution {public: vector grayCode(int n) { vector results; do{ if (n < 0) break; else if (n == 0) { resul

2013-12-24 15:31:00 674

原创 Maximum Subarrary

Find the contiguous subarray within an array (containing at least one number) which has the largest sum.For example, given the array [−2,1,−3,4,−1,2,1,−5,4],the contiguous subarray [4,−1,2,1] ha

2013-10-16 13:18:45 642

原创 [leetcode]

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 order.You may assume no duplicates in the array.

2013-10-08 13:01:56 484

原创 reverse interger

Reverse digits of an integer.Example1: x = 123, return 321Example2: x = -123, return -321Have you thought about this?Here are some good questions to ask before coding. Bonus points for

2013-09-20 13:40:27 770

原创 [leetcode ] word search

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 "adjacent" cells are those horizontally or vertically

2013-03-01 03:20:16 425

原创 Divide Two Integers

class Solution {public: int divide(int dividend, int divisor) { // Start typing your C/C++ solution below // DO NOT write int main() function if (divisor == 0)

2013-02-02 13:07:45 963

原创 Search for a Range !!!

Given a sorted array of integers, find the starting and ending position of a given target value.Your algorithm's runtime complexity must be in the order of O(log n).If the target is not found in t

2013-02-02 08:44:24 365

原创【leetcode】 Populating Next Right Pointers in Each Node

Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; }Populate each next pointer to point to its next right node. If

2013-01-31 11:35:03 305

原创 [leetcode] Rotate List

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->NULL./** * Definition for singly-li

2013-01-28 03:26:48 339

转载求最大prime

不知道这个的复杂度怎么分析。不过worst case 应该是O（n），average 可能是O(sqrt(n))int maxPrime(int n){ assert(n>=0); if(n <= 3) return n; int k = 1; while(n > 1) { ++k; if(k > n / k) ret

2013-01-28 00:50:23 413

转载【leetcode】 generate parenthesis ！！

class Solution { private: vector ret; public: void solve(int dep, int maxDep, int leftNum, int leftNumTotal, string s) { if (leftNumTotal * 2 > maxDep) return;

2013-01-24 14:12:57 466

原创 [leetcode] simplify path

Given an absolute path for a file (Unix-style), simplify it.For example,path = "/home/", => "/home"path = "/a/./b/../../c/", => "/c"Corner Cases:Did you consider the case w

2013-01-23 10:54:05 424

原创 leetcode power (x,n)

1. 考虑double float 的相等，不能仅仅用==表示，是有精度限制的。2. n 大于0，小于0的情况3. if (temp_diveded & 1) result *= base; base *= base; temp_diveded >>= 1;想法很赞！！！！#define AC

2013-01-23 08:08:07 783

原创 [leetcode] Remove Duplicates from Sorted List II

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.For example,Given 1->2->3->3->4->4->5, return 1->2->5.Given 1

2013-01-23 06:49:34 372

转载 Segment a long string into a set of valid words using a dictionary

http://thenoisychannel.com/2011/08/08/retiring-a-great-interview-problem/有牛人能给解释一下为什么是O(2^n) 和 O(n^2)?

2013-01-15 13:24:06 478

转载 given stream of integers, find first 100 large numbers (!!!)

最开始的idea很自然想到用heap，size为100的heap, 计算复杂度为O(nlog100).不如用bubble sort，bubble100次，因为不需要让这100个数sorted，O(100n) = O(n)

2013-01-12 07:19:45 354

转载【FB】

小肥的面经，小肥的代码：http://collabedit.com/gmysb1. 开会的题目，问给一堆会议，每个会议一个开始时间，结束时间，问有没有 overlap2. 如果这些会议有overlap 求最小需要多少房间第二个解法简直是精典！struct Meeting{ double start;

2013-01-10 00:59:54 762

转载 [leetcode]longest Valid Parentheses(!!)

class Solution {public: int longestValidParentheses(string s) { // Start typing your C/C++ solution below // DO NOT write int main() function int nSize = s.size();

2013-01-08 06:00:56 376

原创 [leetcode] integer 与 Roman的转换

1. integer到roman利用了数组的位置的信息class Solution {public: string intToRoman(int num) { // Start typing your C/C++ solution below // DO NOT write int main() function char

2013-01-05 23:54:07 303

原创 [leetcode] Distinct Subsequences

Given a string S and a string T, count the number of distinct subsequences of T in S.A subsequence of a string is a new string which is formed from the original string by deleting some (can be n

2013-01-05 06:04:29 411

原创 [leetcode] Decode Ways (!!)

A message containing letters from A-Z is being encoded to numbers using the following mapping:'A' -> 1'B' -> 2...'Z' -> 26Given an encoded message containing digits, determine the total nu

2013-01-02 02:33:11 560

原创 [leetcode] merge k sort list

/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public: typedef stru

2013-01-01 23:55:27 527

原创 [leetcode] BST与链表的相互转换

1. 链表-->BST (借鉴smile的)/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {} * }; *//** * Definition

2012-12-31 12:17:10 1485

转载 [leetcode] combination （不会做）

Given two integers n and k, return all possible combinations of k numbers out of 1 ... n.For example,If n = 4 and k = 2, a solution is:[ [2,4], [3,4], [2,3], [1,2], [1,3], [1,4

2012-12-31 05:08:40 400

原创 [leetcode] Binary Tree Maximum Path Sum

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 / \ 2 3Return 6.

2012-12-28 09:59:48 359

原创 [leetcode] Best Time to Buy and Sell Stock

Best Time to Buy and Sell StockSay you have an array for which the ith element is the price of a given stock on day i.1 If you were only permitted to complete at most one transaction (i

2012-12-24 01:15:33 409

转载 composite VS. inheritance

原帖link：http://www.javaworld.com/jw-11-1998/jw-11-techniques.html?page=3Inheritance：When you establish an inheritance relationship between two classes, you get to take advantage of dynamic binding

2012-12-22 23:44:23 533

原创 [leetcode] anagrams

Given an array of strings, return all groups of strings that are anagrams.Note: All inputs will be in lower-case.这题原本思路搞得很复杂：1.统计每个string中每个字符的出现次数，然后用“a1b5y4”的形式表示每个字符串。------>其实只要复制string到一个

2012-12-22 11:50:57 432

原创 longest Palindrome substring

class Solution {public: string longestPalindrome(string s) { // Start typing your C/C++ solution below // DO NOT write int main() function int len = s.size(); int

2012-12-22 10:39:27 466

原创【leetcode】 4 sum

4SumGiven an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target.No

2012-12-22 09:38:10 1133

转载找出一个bst中第二大的数

search the most right node from root. If the most right root has no child, return its parent; otherwise return the largest number of its left child tree

2012-12-22 09:33:07 789

转载 deep copy 带有random的linklist

题目:有一个链表L,其每个节点有2个指针，一个指针next指向链表的下个节点，另一个random随机指向链表中的任一个节点，可能是自己或者为空，写一个程序，要求复制这个链表的结构并分析其复杂性解决方法一：O(n)的复杂度,扫面两边即可。缺点：修改了原始的链表

2012-12-20 23:48:58 534

原创 edit distance

Given two words word1 and word2, find the minimum number of steps required to convert word1 to word2. (each operation is counted as 1 step.)You have the following 3 operations permitted on a w

2012-12-20 03:43:20 385

原创 OOD之思路乱发散

每一个object都含有state和method，因此定义一个object的时候一定要说明他的含有什么data member，还有什么method。多用design pattern，少用inheritance；using interfaces1. 设计一个文本编辑器 a）composite pattern来分别管理只读文本和可读写文本 b）singl

2012-12-17 11:37:25 528

转载 reverse bit （！！！）

如果只是reverse一个integer 可以由两种方法1. 两个bit交换typedef unsigned int uint;uint swapBits(uint x, uint i, uint j) { uint lo = ((x >> i) & 1); uint hi = ((x >> j) & 1); if (lo ^ hi) { x ^= ((1U << i

2012-12-17 02:58:05 878

原创 expression 5+4*(7-15) or have parenthesis in any order // 波兰表示法

Answers write code in java /c for expression 5+4*(7-15) or have parenthesis in any order .idea: Use two stack, one for number, one for operator. Every time push a number or an operation into stack.

2012-12-16 22:53:57 506

转载几种sort的优劣势

quicksort有最好的实践效率。同时是in-place。配上random pivot/shuffle，median-of-K 和少量元素转insertion sort是最实用的排序方法。O(n^2)复杂度是极其小概率事件，一般不会发生。同时因为其对硬件cache的应用效率较高，实践中Quicksort很难被beat, 因为cache的访问速度比内存寻址快两个数量级。递归不仅仅

2012-12-14 11:42:17 1444

转载如何用private 构造函数生成instance

static function in class can only access the static data member in the class.private constructor is used to prevent creating instance directly through "new" or other class. 类似于singletonclass p

2012-12-14 02:24:53 556

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