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原创 268. Missing Number

Given an array containing n distinct numbers taken from 0, 1, 2, ..., n, find the one that is missing from the array.Example 1Input: [3,0,1]Output: 2Example 2Input: [9,6,4,2,3,5,7,0,1]Output: 8Not...

2018-03-29 10:53:30 179

Given a string s and a string t, check if s is subsequence of t.You may assume that there is only lower case English letters in both s and t. t is potentially a very long (length ~= 500,000) string, a...

2018-03-28 11:00:59 163

原创 628. Maximum Product of Three Numbers

Given an integer array, find three numbers whose product is maximum and output the maximum product.Example 1:Input: [1,2,3]Output: 6Example 2:Input: [1,2,3,4]Output: 24Note:The length of the given...

2018-03-28 10:47:24 217

原创 328. 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 pla...

2018-02-23 15:46:36 174

原创 398. Random Pick Index

Given an array of integers with possible duplicates, randomly output the index of a given target number. You can assume that the given target number must exist in the array.Note:The array size can be ...

2018-02-22 15:38:22 153

原创 423. Reconstruct Original Digits from English

Given a non-empty string containing an out-of-order English representation of digits 0-9, output the digits in ascending order.Note:Input contains only lowercase English letters.Input is guaranteed to...

2018-02-22 15:17:43 159

原创 452. Minimum Number of Arrows to Burst Balloons

There are a number of spherical balloons spread in two-dimensional space. For each balloon, provided input is the start and end coordinates of the horizontal diameter. Since it's horizontal, y-coordin...

2018-02-22 15:14:41 153

原创 392. Is Subsequence

Given a string s and a string t, check if s is subsequence of t.You may assume that there is only lower case English letters in both s and t. t is potentially a very long (length ~= 500,000) string, a...

2018-02-22 15:00:45 195

原创 744. Find Smallest Letter Greater Than Target

Given a list of sorted characters letters containing only lowercase letters, and given a target letter target, find the smallest element in the list that is larger than the given target.Letters also w...

2018-02-22 14:44:26 174

原创 230. Kth Smallest Element in a BST

Given a binary search tree, write a function kthSmallest to find the kth smallest element in it.Note: You may assume k is always valid, 1 ≤ k ≤ BST's total elements.Follow up:What if the BST is modifi...

2018-02-22 14:40:06 159

原创 543. Diameter of Binary Tree

Given a binary tree, you need to compute the length of the diameter of the tree. The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This path may or may n...

2018-02-22 14:25:18 144

原创 378. Kth Smallest Element in a Sorted Matrix

Given a n x n matrix where each of the rows and columns are sorted in ascending order, find the kth smallest element in the matrix.Note that it is the kth smallest element in the sorted order, not the...

2018-02-22 13:59:41 150

原创 318. Maximum Product of Word Lengths

Given a string array words, find the maximum value of length(word[i]) * length(word[j]) where the two words do not share common letters. You may assume that each word will contain only lower ca...

2018-02-22 13:36:20 169

原创 481. Magical String

A magical string S consists of only '1' and '2' and obeys the following rules:The string S is magical because concatenating the number of contiguous occurrences of characters '1' and '2' generates the...

2018-02-22 13:23:53 148

原创 409. Longest Palindrome

Given a string which consists of lowercase or uppercase letters, find the length of the longest palindromes that can be built with those letters.This is case sensitive, for example "Aa" is not conside...

2018-02-22 13:07:54 130

原创 539. Minimum Time Difference

Given a list of 24-hour clock time points in "Hour:Minutes" format, find the minimum minutes difference between any two time points in the list. Example 1:Input: ["23:59","00:00"]Output: 1Note:The n...

2018-02-21 23:56:47 231

原创 445. Add Two Numbers II

You are given two non-empty linked lists representing two non-negative integers. The most significant digit comes first and each of their nodes contain a single digit. Add the two numbers and return i...

2018-02-21 23:38:01 126

原创 498. Diagonal Traverse

Given a matrix of M x N elements (M rows, N columns), return all elements of the matrix in diagonal order as shown in the below image. Example:Input:[ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ]]Outpu...

2018-02-21 22:50:53 171

原创 357. Count Numbers with Unique Digits

Given a non-negative integer n, count all numbers with unique digits, x, where 0 ≤ x < 10n. Example:Given n = 2, return 91. (The answer should be the total numbers in the range of 0 ≤ x < 100...

2018-02-20 15:56:32 142

原创 623. Add One Row to Tree

Given the root of a binary tree, then value v and depth d, you need to add a row of nodes with value v at the given depth d. The root node is at depth 1. The adding rule is: given a positive integer d...

2018-02-20 15:17:06 173

原创 554. Brick Wall

There is a brick wall in front of you. The wall is rectangular and has several rows of bricks. The bricks have the same height but different width. You want to draw a vertical line from the top to the...

2018-02-20 12:40:41 161

原创 447. Number of Boomerangs

Given n points in the plane that are all pairwise distinct, a "boomerang" is a tuple of points (i, j, k) such that the distance between i and j equals the distance between i and k (the order of the tu...

2018-02-20 12:24:55 130

原创 599. Minimum Index Sum of Two Lists

Suppose Andy and Doris want to choose a restaurant for dinner, and they both have a list of favorite restaurants represented by strings. You need to help them find out their common interest with the l...

2018-02-20 10:41:13 297

原创 144. Binary Tree Preorder Traversal

Given a binary tree, return the preorder traversal of its nodes' values.For example:Given binary tree [1,null,2,3], 1 \ 2 / 3return [1,2,3].Note: Recursive solution is trivial, coul...

2018-02-20 10:19:48 145

原创 343. Integer Break

Given a positive integer n, break it into the sum of at least two positive integers and maximize the product of those integers. Return the maximum product you can get.For example, given n = 2, return ...

2018-02-20 09:58:37 148

转载 46. Permutations

Given a collection of distinct numbers, return all possible permutations.For example,[1,2,3] have the following permutations:[ [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], [3,2,1]]思路：递归。...

2018-02-20 00:28:47 139

原创 206. Reverse Linked List

Reverse a singly linked list.思路：唯一例外在于head，需要指向NULL，所以创立一个新node，使之为NULL代码1：/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) ...

2018-02-20 00:16:25 115

原创 216. Combination Sum III

Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique set of numbers. Example 1:Input: k = 3, ...

2018-02-20 00:05:42 152

原创 697. Degree of an Array

Given a non-empty array of non-negative integers nums, the degree of this array is defined as the maximum frequency of any one of its elements.Your task is to find the smallest possible length of a (c...

2018-02-19 10:42:37 238

原创 217. Contains Duplicate

Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the array, and it should return false if every element is...

2018-02-19 10:30:56 114

原创 506. Relative Ranks

Given scores of N athletes, find their relative ranks and the people with the top three highest scores, who will be awarded medals: "Gold Medal", "Silver Medal" and "Bronze Medal".Example 1:Input: [5,...

2018-02-19 10:22:25 129

原创 530. Minimum Absolute Difference in BST

Given a binary search tree with non-negative values, find the minimum absolute difference between values of any two nodes.Example:Input: 1 \ 3 / 2Output:1Explanation:The mini...

2018-02-18 23:55:51 133

原创 237. Delete Node in a Linked List

Write a function to delete a node (except the tail) in a singly linked list, given only access to that node.Supposed the linked list is 1 -> 2 -> 3 -> 4 and you are given the third node with ...

2018-02-18 23:44:35 114

原创 167. Two Sum II - Input array is sorted

Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number.The function twoSum should return indices of the two numbers su...

2018-02-17 19:45:31 114

原创 455. Assign Cookies

Assume you are an awesome parent and want to give your children some cookies. But, you should give each child at most one cookie. Each child i has a greed factor gi, which is the minimum size of a coo...

2018-02-17 19:36:36 203

原创 387. First Unique Character in a String

Given a string, find the first non-repeating character in it and return it's index. If it doesn't exist, return -1.Examples:s = "leetcode"return 0.s = "loveleetcode",return 2.Note: You may assume...

2018-02-17 19:25:38 128

原创 242. Valid Anagram

Given two strings s and t, write a function to determine if t is an anagram of s. For example,s = "anagram", t = "nagaram", return true.s = "rat", t = "car", return false.Note:You may assume the strin...

2018-02-17 19:11:43 173

原创 563. Binary Tree Tilt

Given a binary tree, return the tilt of the whole tree.The tilt of a tree node is defined as the absolute difference between the sum of all left subtree node values and the sum of all right subtree no...

2018-02-17 18:59:52 131

原创 384. Shuffle an Array

Shuffle a set of numbers without duplicates.Example:// Init an array with set 1, 2, and 3.int[] nums = {1,2,3};Solution solution = new Solution(nums);// Shuffle the array [1,2,3] and return its re...

2018-02-17 17:09:05 189

原创 22. 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:[ "((()))", "(()())", "(())()", "()(())", "...

2018-02-17 16:55:45 143

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