sherry612-优快云博客

原创 [Leetcode] Sort List

题目： Sort a linked list in O(n log n) time using constant space complexity. 思路：O(nlogn)的sort有quick sort, merge sort, heap sort. 首先排除heap sort, heap需要用到O(n)的空间。其次排除quick sort,

2014-11-30 10:14:54 318

原创 [Leetcode] Next Permutation

题目： 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 shoul

2014-11-13 09:56:00 352

原创 [Leetcode] Reverse Nodes in k-Group

题目： 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

2014-11-10 06:27:06 315

原创 [Leetcode] Container With Most Water

题目： 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 co

2014-11-10 05:05:34 302

原创 [Leetcode] Palindrome Number

题目： 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 co

2014-11-10 04:54:59 283

原创 [Leetcode] Longest Palindromic Substring

题目： 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. 思路：

2014-11-10 04:41:49 250

原创 [Leetcode] Permutations II

题目： Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example, [1,1,2] have the following unique permutations: [1,1,2], [1,2,1],

2014-11-06 14:05:23 332

原创 [Leetcode] Minimum Window Substring

题目： 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

2014-11-06 11:43:27 439

原创 [Leetcode] Longest Substring Without Repeating Characters

题目： 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

2014-11-06 10:36:59 250

原创 [Leetcode] Palindrome Partitioning II

题目： Given a 2D board containing 'X' and 'O', capture all regions surrounded by 'X'. A region is captured by flipping all 'O's into 'X's in that surrounded region. For example, X

2014-11-01 04:29:12 276

原创 [Leetcode] Surrounded Regions

题目： Given an unsorted array of integers, find the length of the longest consecutive elements sequence. For example, Given [100, 4, 200, 1, 3, 2], The longest consecutive elements sequence is

2014-10-27 11:07:50 389

原创 [Leetcode] Longest Consecutive Sequence

题目： Given a binary tree, flatten it to a linked list in-place. For example, Given 1 / \ 2 5 / \ \ 3 4 6 The flattened tree should look like:

2014-10-24 10:33:58 271

原创 [Leetcode] Populating Next Right Pointers in Each Node II

题目： Follow up for problem "Populating Next Right Pointers in Each Node". What if the given tree could be any binary tree? Would your previous solution still work? Note: You may only

2014-10-22 12:15:35 285

原创 [Leetcode] Populating Next Right Pointers in Each Node

题目： Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its next

2014-10-22 11:28:39 275

原创 [Leetcode] Flatten Binary Tree to Linked List

题目： Given a binary tree, flatten it to a linked list in-place. For example, Given 1 / \ 2 5 / \ \ 3 4 6 The flattened tree should loo

2014-10-22 11:13:01 275

原创 [Leetcode] Path Sum II

题目： Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example: Given the below binary tree and sum = 22, 5

2014-10-22 10:54:13 273

原创 [Leetcode] Path Sum

题目： Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST. 思路：类似二分法，中间向左右两边找child. class Solution { public: int tr

2014-10-22 10:49:00 248

原创 [Leetcode] Convert Sorted List to Binary Search Tree

题目： Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST. 思路：类似二分法，中间向左右两边找child. class Solution { public: TreeNo

2014-10-22 10:31:40 304

原创 [Leetcode] Convert Sorted Array to Binary Search Tree

题目： Given inorder and postorder traversal of a tree, construct the binary tree. Note: You may assume that duplicates do not exist in the tree. 思路：in order遍历后的数组为[left_tree, r

2014-10-22 10:20:34 249

原创 [Leetcode] Construct Binary Tree from Preorder and Inorder Traversal

题目： Given inorder and postorder traversal of a tree, construct the binary tree. Note: You may assume that duplicates do not exist in the tree. 思路：in order遍历后的数组为[left_tree, r

2014-10-22 10:04:45 326

原创 [Leetcode] Construct Binary Tree from Inorder and Postorder Traversal

题目： Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between). For example:

2014-10-22 09:39:48 251

原创 [Leetcode] Binary Tree Zigzag Level Order Traversal

题目： Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between). For ex

2014-10-21 05:06:35 283

原创 [Leetcode] Restore IP Addresses

题目： Given a string containing only digits, restore it by returning all possible valid IP address combinations. For example: Given "25525511135", return ["255.255.11.135", "255.255.

2014-10-21 04:30:46 238

原创 [Leetcode] Partition List

题目： 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 original relative order of the nod

2014-10-21 04:05:37 243

原创 [Leetcode] Remove Duplicates from Sorted List II

题目： Given a sorted linked list, delete all duplicates such that each element appear only once. For example, Given 1->1->2, return 1->2. Given 1->1->2->3->3, return 1->2->3. 思路：两个指

2014-10-21 03:49:03 548

原创 [Leetcode] Remove Duplicates from Sorted List

题目： Given a sorted linked list, delete all duplicates such that each element appear only once. For example, Given 1->1->2, return 1->2. Given 1->1->2->3->3, return 1->2->3.

2014-10-21 03:21:55 272

原创 [Leetcode] Search in Rotated Sorted Array II

题目： Follow up for "Search in Rotated Sorted Array": What if duplicates are allowed? Would this affect the run-time complexity? How and why? Write a function to determine if a given tar

2014-10-21 03:07:54 264

原创 [Leetcode] Search a 2D Matrix

题目： 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 fi

2014-10-21 02:49:00 234

原创 [Leetcode] Edit Distance

题目： 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 per

2014-10-21 02:31:20 256

原创 [Leetcode] Minimum Path Sum

题目： Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path. Note: You can only move either

2014-10-21 00:39:57 258

原创 [Leetcode] Unique Paths II

题目： A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below). The robot can only move either down or right at any point in time. The robot is trying to r

2014-10-21 00:24:38 236

原创 [Leetcode] Unique Paths

题目： Follow up for N-Queens problem. Now, instead outputting board configurations, return the total number of distinct solutions. 思路：回溯法，和N-Queens I基本一样。 class Solution {

2014-10-21 00:09:52 231

原创 [Leetcode] Maximum Subarray

题目： Follow up for N-Queens problem. Now, instead outputting board configurations, return the total number of distinct solutions. 思路：回溯法，和N-Queens I基本一样。 class Solution {

2014-10-20 11:25:01 290

原创 [Leetcode] N-Queens II

题目： The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other. Given an integer n, return all distinct solutions to the n-

2014-10-20 07:07:58 244

原创 [Leetcode] N-Queens

题目： The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other. Given an integer n, return all distinct solutio

2014-10-20 05:36:20 234

原创 [Leetcode] Multiply Strings

题目： Given two numbers represented as strings, return multiplication of the numbers as a string. Note: The numbers can be arbitrarily large and are non-negative. 思路：递归寻找所有可能。

2014-10-20 01:56:00 257

原创 [Leetcode] Combination Sum II

题目： 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

2014-10-18 09:49:30 215

原创 [Leetcode] Combination Sum

题目： 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 t

2014-10-18 09:36:30 257

原创 [Leetcode] Search for a Range

题目： 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

2014-10-18 05:39:10 259

原创 [Leetcode] Search in Rotated Sorted Array

题目： Divide two integers without using multiplication, division and mod operator. 思路：D = a0 * d * 2^n + a1 * d * 2^(n-1) + ... + an * d * 2^0，从d * 2^n开始，不断的用被除数减去这个值，同时计算ai. 最终

2014-10-18 04:59:27 251

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