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原创【LeetCode】 143. 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 {1,4

2017-02-12 00:13:42 214

原创【LeetCode】 142. Linked List Cycle II

Given a linked list, return the node where the cycle begins. If there is no cycle, return null. Note: Do not modify the linked list. Follow up: Can you solve it without using extra space?

2017-02-11 23:45:52 209

原创【LeetCode】 092. 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. Note: Given m, n satisfy the

2017-02-11 23:44:50 179

原创【LeetCode】 082. 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->1-

2017-02-11 23:43:12 229

原创【LeetCode】 086. Partition List

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 nodes in each of

2017-01-31 13:52:21 171

原创【LeetCode】 113. Path Sum II

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 / \

2017-01-28 04:42:05 156

原创【LeetCode】 147. Insertion Sort List

Sort a linked list using insertion sort. /** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int x) { val = x; } * } */

2017-01-28 03:35:22 194

原创【LeetCode】 049. Group Anagrams

Given an array of strings, group anagrams together. For example, given: ["eat", "tea", "tan", "ate", "nat", "bat"], Return: [ ["ate", "eat","tea"], ["nat","tan"], ["bat"] ] Note: Al

2017-01-28 02:06:17 152

原创【LeetCode】 109. Convert Sorted List to Binary Search Tree

Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST. /** * Definition for singly-linked list. * public class ListNode { * int val

2017-01-28 00:42:35 123

原创【LeetCode】 236. Lowest Common Ancestor of a Binary Tree

Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree. According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two node

2017-01-26 05:36:57 128

原创【LeetCode】 397. Integer Replacement

Given a positive integer n and you can do operations as follow: If n is even, replace n with n/2.If n is odd, you can replace n with either n + 1 or n - 1. What is the minimum number o

2017-01-26 05:12:23 204

原创【LeetCode】 081. Search in Rotated Sorted Array II

Follow up for "Search in Rotated Sorted Array": What if duplicates are allowed? Would this affect the run-time complexity? How and why? Suppose an array sorted in ascending order is rotated at

2017-01-26 04:47:46 192

原创【LeetCode】 114. 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 6 The flattened tree should look like: 1

2017-01-26 04:36:20 180

原创【LeetCode】 055. Jump Game

Given an array of non-negative integers, you are initially positioned at the first index of the array. Each element in the array represents your maximum jump length at that position. Determine i

2017-01-25 04:32:24 264

原创【LeetCode】 201. Bitwise AND of Numbers Range

Given a range [m, n] where 0 For example, given the range [5, 7], you should return 4. public class Solution { public int rangeBitwiseAnd(int m, int n) { if(m == 0){ ret

2017-01-25 03:14:35 133

原创【LeetCode】 275. H-Index II

Follow up for H-Index: What if the citations array is sorted in ascending order? Could you optimize your algorithm? Hint: Expected runtime complexity is in O(log n) and the input is sorted.

2017-01-25 02:05:59 172

原创【LeetCode】 274. H-Index

Given an array of citations (each citation is a non-negative integer) of a researcher, write a function to compute the researcher's h-index. According to the definition of h-index on Wikipedia: "A

2017-01-24 13:06:59 194

原创【LeetCode】 289. Game of Life

According to the Wikipedia's article: "The Game of Life, also known simply as Life, is a cellular automaton devised by the British mathematician John Horton Conway in 1970." Given a board with m

2017-01-24 12:40:56 171

原创【LeetCode】 395. Longest Substring with At Least K Repeating Characters

Find the length of the longest substring T of a given string (consists of lowercase letters only) such that every character in T appears no less than k times. Example 1: Input: s = "aaabb", k =

2017-01-24 10:40:34 447

原创【LeetCode】 491. Increasing Subsequences

Given an integer array, your task is to find all the different possible increasing subsequences of the given array, and the length of an increasing subsequence should be at least 2 . Example: In

2017-01-23 09:25:02 1826

原创【LeetCode】 284. Peeking Iterator

Given an Iterator class interface with methods: next() and hasNext(), design and implement a PeekingIterator that support the peek()operation -- it essentially peek() at the element that will be r

2017-01-23 08:09:58 254

原创【LeetCode】 090. Subsets II

Given a collection of integers that might contain duplicates, nums, return all possible subsets. Note: The solution set must not contain duplicate subsets. For example, If nums = [1,2,2], a sol

2017-01-23 07:16:59 160

原创【LeetCode】 388. Longest Absolute File Path

Suppose we abstract our file system by a string in the following manner: The string "dir\n\tsubdir1\n\tsubdir2\n\t\tfile.ext" represents: dir subdir1 subdir2 file.ext The direc

2017-01-23 06:58:58 133

原创【LeetCode】 376. Wiggle Subsequence

A sequence of numbers is called a wiggle sequence if the differences between successive numbers strictly alternate between positive and negative. The first difference (if one exists) may be either pos

2017-01-23 02:30:21 152

原创【LeetCode】 080. Remove Duplicates from Sorted Array II

Follow up for "Remove Duplicates": What if duplicates are allowed at most twice? For example, Given sorted array nums = [1,1,1,2,2,3], Your function should return length = 5, with the first fi

2017-01-23 02:25:58 236

原创【LeetCode】 375. Guess Number Higher or Lower II

We are playing the Guess Game. The game is as follows: I pick a number from 1 to n. You have to guess which number I picked. Every time you guess wrong, I'll tell you whether the number I pi

2017-01-23 00:41:56 150

原创【LeetCode】 073. Set Matrix Zeroes

Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place. click to show follow up. Follow up: Did you use extra space? A straight forward solution using O(m

2017-01-22 10:27:50 517

原创【LeetCode】 450. Delete Node in a BST

Given a root node reference of a BST and a key, delete the node with the given key in the BST. Return the root node reference (possibly updated) of the BST. Basically, the deletion can be divided i

2017-01-22 00:05:21 160

原创【LeetCode】 279. Perfect Squares

Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, ...) which sum to n. For example, given n = 12, return 3 because 12 = 4 + 4 + 4; given n =

2017-01-21 08:38:43 207

原创【LeetCode】 129. Sum Root to Leaf Numbers

Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number. An example is the root-to-leaf path 1->2->3 which represents the number 123. Find the tota

2017-01-21 07:32:36 115

原创【LeetCode】 074. Search a 2D Matrix

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 first integer of each

2017-01-20 10:01:01 146

原创【LeetCode】 039. Combination Sum

Given a set of candidate numbers (C) (without duplicates) 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

2017-01-20 09:34:09 120

原创【LeetCode】 474. Ones and Zeroes

In the computer world, use restricted resource you have to generate maximum benefit is what we always want to pursue. For now, suppose you are a dominator of m 0s and n 1s respectively. On the ot

2017-01-20 09:14:19 165

原创【LeetCode】 162. Find Peak Element

A peak element is an element that is greater than its neighbors. Given an input array where num[i] ≠ num[i+1], find a peak element and return its index. The array may contain multiple peaks, in

2017-01-20 07:30:48 121

原创【LeetCode】 075. 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

2017-01-18 05:58:19 104

原创【LeetCode】 116. 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.

2017-01-18 03:27:19 104

原创【LeetCode】 313. Super Ugly Number

Write a program to find the nth super ugly number. Super ugly numbers are positive numbers whose all prime factors are in the given prime list primes of size k. For example, [1, 2, 4, 7, 8, 13,

2017-01-18 00:22:40 96

原创【LeetCode】 048. 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? public class Solution { public void rotat

2017-01-17 05:59:43 135

原创【LeetCode】 064. 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. Note: You can only move either down or right at

2017-01-17 05:41:40 158

原创【LeetCode】 300. Longest Increasing Subsequence

Given an unsorted array of integers, find the length of longest increasing subsequence. For example, Given [10, 9, 2, 5, 3, 7, 101, 18], The longest increasing subsequence is [2, 3, 7, 101], ther

2017-01-17 05:30:47 128

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