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原创 Leetcode Candy

There are N children standing in a line. Each child is assigned a rating value.You are giving candies to these children subjected to the following requirements:Each child must have at least on

2016-07-29 05:23:57 368

原创 Leetcode Reverse Linked List II

Reverse a linked list from position m to n. Do it in-place and in one-pass.For example:Given 1->2->3->4->5->NULL, m = 2 and n = 4,return 1->4->3->2->5->NULL.Diffiiculty: Medium/**

2016-07-29 05:22:43 276

原创 Leetcode Flatten Binary Tree to Linked List

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

2016-07-29 05:21:50 291

原创 Leetcode Minimum Path Sum

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.Difficulty: Mediumpublic class Soluti

2016-07-29 05:20:45 245

原创 Leetcode Substring with Concatenation of All Words

You are given a string, s, and a list of words, words, that are all of the same length. Find all starting indices of substring(s) in s that is a concatenation of each word in words exactly once and

2016-07-29 05:19:24 240

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.

2016-07-29 05:17:48 264

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.Difficulty: Medium/** * De

2016-07-27 05:21:56 216

原创 Leetcode Fraction to Recurring Decimal

Given two integers representing the numerator and denominator of a fraction, return the fraction in string format.If the fractional part is repeating, enclose the repeating part in parentheses.

2016-07-27 05:20:55 251

原创 Leetcode Missing Number

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, 3] return 2.Note:Your algorithm shoul

2016-07-27 05:19:21 230

原创 Leetcode Convert Sorted Array to Binary Search Tree

Given an array where elements are sorted in ascending order, convert it to a height balanced BST.Difficulty: Medium/** * Definition for a binary tree node. * public class TreeNode { *

2016-07-27 05:18:22 282

原创 Leetcode Binary Tree Preorder Traversal

Given a binary tree, return the preorder traversal of its nodes' values.For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3return [1,2,3].Note: Recursive soluti

2016-07-27 05:17:31 226

原创 Leetcode Word Ladder II

Given two words (beginWord and endWord), and a dictionary's word list, find all shortest transformation sequence(s) from beginWord toendWord, such that:Only one letter can be changed at a timeEach

2016-07-27 05:14:39 299

原创 Leetcode Minimum Depth of Binary Tree

Given a binary tree, find its minimum depth.The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.Difficulty: Easy/** * Defin

2016-07-27 05:13:19 202

原创 Leetcode Sum of Two Integers

Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -.Example:Given a = 1 and b = 2, return 3.Difficulty: EasySolution: Bit Manipulationpubli

2016-07-27 05:10:14 245

原创 Leetcode Contains Duplicate III

Given an array of integers, find out whether there are two distinct indices i and j in the array such that the difference between nums[i] andnums[j] is at most t and the difference between i and

2016-07-22 01:17:40 238

原创 Leetcode Clone Graph

Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.OJ's undirected graph serialization:Nodes are labeled uniquely.We use # as a separator for each

2016-07-21 23:34:01 230

原创 Leetcode Subsets

Given a set of distinct integers, nums, return all possible subsets.Note: The solution set must not contain duplicate subsets.For example,If nums = [1,2,3], a solution is:[ [3], [1],

2016-07-21 23:32:56 211

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

2016-07-21 23:31:58 203

原创 Leetcode Wildcard Matching

Implement wildcard pattern matching with support for '?' and '*'.'?' Matches any single character.'*' Matches any sequence of characters (including the empty sequence).The matching should cover t

2016-07-21 23:30:24 204

原创 Leetcode Unique Paths II

Follow up for "Unique Paths":Now consider if some obstacles are added to the grids. How many unique paths would there be?An obstacle and empty space is marked as 1 and 0 respectively in the

2016-07-21 23:27:04 184

原创 Leetcode Unique Paths

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 reach the

2016-07-21 21:14:30 177

原创 Leetcode Multiply Strings

Given two numbers represented as strings, return multiplication of the numbers as a string.Difficulty: Mediumpublic class Solution { public String multiply(String num1, String num2) {

2016-07-20 03:51:32 135

原创 Leetcode Length of Last Word

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 does not exist, return 0.Note: A word is

2016-07-20 03:50:36 182

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.

2016-07-20 03:49:35 130

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

2016-07-20 03:48:13 194

原创 Leetcode Maximal Rectangle

Given a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing all ones and return its area.Difficulty: HardSolution: http://www.programcreek.com/2014/05/leetcode-ma

2016-07-20 03:46:40 180

原创 Leetcode Binary Tree Maximum Path Sum

Given a binary tree, find the maximum path sum.For this problem, a path is defined as any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The

2016-07-20 03:44:28 129

原创 Leetcode Odd Even Linked List

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 value in the nodes.You should try to do it in

2016-07-20 03:43:19 145

原创 Reorder List

Given a singly linked list L: L0→L1→…→Ln-1→Ln,reorder it to: L0→Ln→L1→Ln-1→L2→Ln-2→…You must do this in-place without altering the nodes' values.For example,Given {1,2,3,4}, reorder it to

2016-07-20 03:41:55 208

原创 Leetcode Remove Duplicates from Sorted List

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.Difficulty: Easy/

2016-07-20 03:40:18 184

原创 Leetcode Path Sum

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.For example:Given the below binary tree and sum

2016-07-20 03:38:34 146

原创 Leetcode Power of Two/Three/Four

Given an integer, write a function to determine if it is a power of two/three/four.Difficulty: Easypublic class Solution { public boolean isPowerOfTwo(int n) { if(n <= 0) return

2016-07-20 03:36:44 196

原创 Leetcode Rotate Image

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?Difficulty: Mediumpublic class Solution {

2016-07-20 03:34:10 134

原创 Leetcode Sort Colors

Given an array with n objects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order red, white and blue.Here, we will use the integers

2016-07-20 01:20:42 129

原创 Leetcode Gas Station

There are N gas stations along a circular route, where the amount of gas at station i is gas[i].You have a car with an unlimited gas tank and it costs cost[i] of gas to travel from station i to

2016-07-20 01:11:59 164

原创 Leetcode Rectangle Area

Find the total area covered by two rectilinear rectangles in a 2D plane.Each rectangle is defined by its bottom left corner and top right corner as shown in the figure.Assume that the tota

2016-07-20 01:09:05 169

原创 Leetcode Triangle

Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers on the row below.For example, given the following triangle[ [2], [3,4], [

2016-07-20 01:06:51 217

You are a product manager and currently leading a team to develop a new product. Unfortunately, the latest version of your product fails the quality check. Since each version is developed based on the

2016-07-20 00:57:56 159

原创 Leetcode Reverse Bits

Reverse bits of a given 32 bits unsigned integer.For example, given input 43261596 (represented in binary as 00000010100101000001111010011100), return 964176192 (represented in binary as 001110010

2016-07-19 05:11:33 160

原创 Leetcode 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 word:

2016-07-19 05:10:03 145

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