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原创 LeetCode-Maximum Product Subarray

Find the contiguous subarray within an array (containing at least one number) which has the largest product.For example, given the array [2,3,-2,4],the contiguous subarray [2,3] has the larges

2014-09-25 02:28:23 489

原创 LeetCode-Integer to Roman

Given an integer, convert it to a roman numeral.Input is guaranteed to be within the range from 1 to 3999.Solution:Code:class Solution {public: string intToRoman(int num) { vect

2014-09-21 03:34:11 481

原创 LeetCode-Roman to Integer

Given a roman numeral, convert it to an integer.Input is guaranteed to be within the range from 1 to 3999.Solution:Code:class Solution {public: int getRomanValue(char c) { swi

2014-09-21 03:24:23 443

原创 LeetCode-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, and there exists one unique longest palindromic substring.Solution:Code:

2014-09-21 02:19:55 462

原创 LeetCode-Two Sum

Given an array of integers, find two numbers such that they add up to a specific target number.The function twoSum should return indices of the two numbers such that they add up to the target, whe

2014-08-19 18:54:55 458

原创 LeetCode-Median of Two Sorted Arrays

There are two sorted arrays A and B of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)).Solution:Code:class Solution

2014-08-19 14:55:39 387

原创 LeetCode-Longest Substring Without Repeating Characters

Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters for "abcabcbb" is "abc", which the length is 3. Fo

2014-08-19 14:10:27 366

You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a link

2014-08-19 13:44:16 443

原创 LeetCode-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)P A H NA P L S I

2014-08-19 13:25:07 289

原创 LeetCode-Reverse Integer

Reverse digits of an integer.Example1: x = 123, return 321Example2: x = -123, return -321click to show spoilers.Have you thought about this?Here are some good questions to ask before c

2014-08-18 21:44:03 326

原创 LeetCode-String to Integer (atoi)

Implement atoi to convert a string to an integer.Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input ca

2014-08-18 21:31:39 317

原创 LeetCode-Palindrome Number

Determine whether an integer is a palindrome. Do this without extra space.click to show spoilers.Some hints:Could negative integers be palindromes? (ie, -1)If you are thinking of convertin

2014-08-18 21:18:37 364

原创 LeetCode-Regular Expression Matching

Implement regular expression matching with support for '.' and '*'.'.' Matches any single character.'*' Matches zero or more of the preceding element.The matching should cover the entire input st

2014-08-18 19:55:07 701

原创 LeetCode-Container With Most Water

Given n non-negative integers a1, a2, ..., an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of line i is at (i, ai) and (i, 0). Fin

2014-08-18 14:53:53 367

原创 LeetCode-Longest Common Prefix

Write a function to find the longest common prefix string amongst an array of strings.Solution:Code:

2014-08-18 14:31:23 428

原创 LeetCode-3Sum

Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.Note:Elements in a triplet (a,b,c

2014-08-18 14:19:40 398

原创 LeetCode-3Sum Closest

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. You may assume that each input would have exact

2014-08-18 14:02:30 312

原创 LeetCode-4Sum

Given 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.Note:Element

2014-08-18 13:45:03 308

原创 LeetCode-Letter Combinations of a Phone Number

Given a digit string, return all possible letter combinations that the number could represent.A mapping of digit to letters (just like on the telephone buttons) is given below.Input:Digit st

2014-08-18 12:01:34 511

原创 LeetCode-Remove Nth Node From End of List

Given a linked list, remove the nth node from the end of list and return its head.For example, Given linked list: 1->2->3->4->5, and n = 2. After removing the second node from the end, the

2014-08-18 11:41:31 340

原创 LeetCode-Valid Parentheses

Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.The brackets must close in the correct order, "()" and "()[]{}" are all va

2014-08-18 11:23:22 308

原创 LeetCode-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:"((()))", "(()())", "(())()", "()(())", "()()

2014-08-18 11:13:33 278

原创 LeetCode-Merge k Sorted Lists

Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.Solution:Code:

2014-08-17 22:59:19 305

原创 LeetCode-Swap Nodes in Pairs

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 algorithm should use only constant space. Y

2014-08-17 22:27:14 266

原创 LeetCode-Reverse Nodes in k-Group

Given a linked list, reverse the nodes of a linked list k at a time and return its modified list.If the number of nodes is not a multiple of k then left-out nodes in the end should remain as it is

2014-08-17 22:11:28 408

原创 LeetCode-Remove Duplicates from Sorted Array

Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length.Do not allocate extra space for another array, you must do this in place with

2014-08-17 19:09:30 277

原创 LeetCode-Remove Element

Given an array and a value, remove all instances of that value in place and return the new length.The order of elements can be changed. It doesn't matter what you leave beyond the new length.S

2014-08-17 19:03:41 303

原创 LeetCode-Implement strStr()

Implement strStr().Returns a pointer to the first occurrence of needle in haystack, or null if needle is not part of haystack.Solution:Code:

2014-08-17 18:44:38 300

原创 LeetCode-Divide Two Integers

Divide two integers without using multiplication, division and mod operator.Solution:Code:

2014-08-17 17:29:40 395

原创 LeetCode-Substring with Concatenation of All Words

You are given a string, S, and a list of words, L, that are all of the same length. Find all starting indices of substring(s) in S that is a concatenation of each word in L exactly once and without an

2014-08-17 17:11:36 318

原创 LeetCode-Next Permutation

Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.If such arrangement is not possible, it must rearrange it as the lowest possible

2014-08-17 14:48:00 333

原创 LeetCode-Longest Valid Parentheses

Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring.For "(()", the longest valid parentheses substring is "()",

2014-08-17 14:31:18 301

原创 LeetCode-Search in Rotated Sorted Array

Suppose a sorted array 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 target value to search. If found in the array retur

2014-08-16 22:22:12 472

原创 LeetCode-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

2014-08-16 17:11:50 366

原创 LeetCode-Search Insert Position

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.

2014-08-16 16:54:39 278

原创 LeetCode-Valid Sudoku

Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.The Sudoku board could be partially filled, where empty cells are filled with the character '.'.A partially fille

2014-08-16 16:07:51 290

原创 LeetCode-Sudoku Solver

Write a program to solve a Sudoku puzzle by filling the empty cells.Empty cells are indicated by the character '.'.You may assume that there will be only one unique solution.A sudoku

2014-08-16 15:55:55 358

原创 LeetCode-Count and Say

The count-and-say sequence is the sequence of integers beginning as follows:1, 11, 21, 1211, 111221, ...1 is read off as "one 1" or 11.11 is read off as "two 1s" or 21.21 is read off as

2014-08-16 13:28:03 335

原创 LeetCode-Combination Sum

Given a set of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.The same repeated number may be chosen from C unlimited numb

2014-08-15 22:13:46 262

原创 LeetCode-Combination Sum II

Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.Each number in C may only be used once in the combina

2014-08-15 22:09:07 366

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