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RSS订阅原创 Top K Frequent Elements
Given a non-empty array of integers, return the k most frequent elements.For example,Given [1,1,1,2,2,3] and k = 2, return [1,2].Note: You may assume k is always valid, 1 ≤ k ≤ number
2016-05-11 10:18:01
518
原创 [LeetCode]Integer Break
Integer BreakGiven 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 exampl
2016-04-19 14:54:46
936
原创 [LeetCode]LRU Cache
Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations: get and set.get(key) - Get the value (will always be positive) of the key if
2016-04-18 20:20:51
485
原创 [LeetCode]Power of Four
Given an integer (signed 32 bits), write a function to check whether it is a power of 4.Example:Given num = 16, return true. Given num = 5, return false.Follow up: Could you solve it without
2016-04-18 16:08:38
408
原创 [LeetCode]Repeated DNA Sequences
All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T, for example: "ACGAATTCCG". When studying DNA, it is sometimes useful to identify repeated sequences within the DNA.Wri
2016-04-18 16:03:02
429
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
2016-04-17 21:32:15
363
原创 [LeetCode]Word Ladder II
Word Ladder II Given two words (beginWord and endWord), and a dictionary's word list, find all shortest transformation sequence(s) from beginWord to endWord, such that:Only one lette
2016-04-17 19:06:25
452
原创 [LeetCode]Basic Calculator
Implement a basic calculator to evaluate a simple expression string.The expression string may contain open ( and closing parentheses ), the plus + or minus sign -, non-negative integers and em
2016-03-30 13:52:57
351
原创 [LeetCode]Insertion Sort List
Sort a linked list using insertion sort.写个子函数把最后一个节点插入到合适的位置。注意每次插入后链表值改变了。class Solution {public: ListNode* insertionSortList(ListNode* head) { if(head == nullptr) return nul
2016-03-29 17:07:09
319
原创 [LeetCode]H-Index II
Follow up for H-Index: What if the citations array is sorted in ascending order? Could you optimize your algorithm?对排好序的求H index，可以想到采用Binary Search。把搜寻规则稍微改一下。class Solution {public: int
2016-03-29 14:33:42
405
原创 [LeetCode]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
2016-03-29 13:21:02
430
原创 [LeetCode]Different Ways to Add Parentheses
Given a string of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operators. The valid operators are +,- and *.Example 1I
2016-03-28 14:23:13
318
原创 [LeetCode]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.Ensure that numbers wi
2016-03-27 12:58:44
325
原创 [LeetCode] House Robber III
The thief has found himself a new place for his thievery again. There is only one entrance to this area, called the "root." Besides the root, each house has one and only one parent house. After a tour
2016-03-26 17:08:59
398
原创 [LeetCode]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 case le
2016-03-26 16:19:06
425
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 sho
2016-03-26 14:08:57
332
原创 [LeetCode]Single Number III
Given an array of numbers nums, in which exactly two elements appear only once and all the other elements appear exactly twice. Find the two elements that appear only once.For example:Given
2016-03-26 14:00:04
384
原创 [LeetCode]Count Primes
Description:Count the number of prime numbers less than a non-negative number, n.参考https://en.wikipedia.org/wiki/Sieve_of_Eratosthenesclass Solution {public: int countPrimes(int n
2016-03-26 10:51:08
308
原创 [LeetCode]Palindrome Linked List
Given a singly linked list, determine if it is a palindrome.利用之前完成的link 翻转。首先找到中间节点，然后对后半link翻转和前半段对比。如果一样说明link是回文。/** * Definition for singly-linked list. * struct ListNode { * int val;
2016-03-26 10:25:33
328
原创 [LeetCode]Binary Tree Paths
Given a binary tree, return all root-to-leaf paths.For example, given the following binary tree: 1 / \2 3 \ 5All root-to-leaf paths are:["1->2->5", "1->3"]中序遍
2016-03-25 20:41:46
336
原创 [LeetCode]Ugly Number
Write a program to check whether a given number is an ugly number.Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 6, 8 are ugly while 14 is not ugly sinc
2016-03-25 20:09:43
275
原创 [LeetCode]Add Digits
Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.For example:Given num = 38, the process is like: 3 + 8 = 11, 1 + 1 = 2. Since 2 has on
2016-03-25 19:55:02
308
原创 [LeetCode]Palindrome Pairs
Given a list of unique words. Find all pairs of distinct indices (i, j) in the given list, so that the concatenation of the two words, i.e. words[i] + words[j] is a palindrome.Example 1:Give
2016-03-25 19:38:41
535
原创 [LeetCode]Count of Range Sum
Given an integer array nums, return the number of range sums that lie in [lower, upper] inclusive.Range sum S(i, j) is defined as the sum of the elements in nums between indices i and j (i ≤ j),
2016-03-25 18:20:11
606
原创 C++ String类的实现
训练下实现String类。要完全写好还是有很多细节要注意的。#include #includeclass string{ friend std::ostream& operator<<(std::ostream& os,const string &a);//必须声明为友元函数，不是成员函数，返回的是ostream对象 friend std::istream& operat
2016-03-08 22:06:04
411
原创 [LeetCode]Increasing Triplet Subsequence
Given an unsorted array return whether an increasing subsequence of length 3 exists or not in the array.Formally the function should:Return true if there exists i, j, k such that arr[i] ar
2016-03-04 10:45:06
364
原创 [LeetCode]Self Crossing
You are given an array x of n positive numbers. You start at point (0,0) and moves x[0] metres to the north, then x[1] metres to the west, x[2] metres to the south,x[3] metres to the east and so
2016-03-03 20:19:44
1513
原创 [LeetCode]Longest Increasing Path in a Matrix
Given an integer matrix, find the length of the longest increasing path.From each cell, you can either move to four directions: left, right, up or down. You may NOT move diagonally or move outside
2016-03-02 14:31:05
501
原创 [LeetCode]Surrounded Regions
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 X X XX O O X
2016-03-01 23:29:06
750
原创 Implement Trie (Prefix Tree)
mplement a trie with insert, search, and startsWith methods.Note:You may assume that all inputs are consist of lowercase letters a-z.关于前缀树的知识见https://en.wikipedia.org/wiki/Trie因为题目中说道字母在
2016-02-29 13:53:35
381
原创 [LeetCode]Populating Next Right Pointers in Each Node II
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 use constant
2015-12-30 15:17:23
368
原创 [LeetCode]Distinct Subsequences
Given a string S and a string T, count the number of distinct subsequences of T in S.A subsequence of a string is a new string which is formed from the original string by deleting some (can be non
2015-12-30 13:49:11
475
原创 [LeetCode]Binary Tree Level Order Traversal II
Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root).For example:Given binary tree {3,9,20,#,#,15,7},
2015-12-29 16:33:37
346
原创 [LeetCode]Construct Binary Tree from Inorder and Postorder Traversal
Given inorder and postorder traversal of a tree, construct the binary tree.递归实现/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * Tree
2015-12-29 15:49:05
340
原创 [LeetCode]Construct Binary Tree from Preorder and Inorder Traversal
Given preorder and inorder traversal of a tree, construct the binary tree.由树的前序遍历和中序遍历来构建子树。首先找到根节点，然后递归找到左侧和右侧根节点完成。/** * Definition for a binary tree node. * struct TreeNode { * int val
2015-12-29 15:29:07
405
原创 [LeetCode]Binary Tree Zigzag Level Order Traversal
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:Given binary
2015-12-26 17:15:28
295
原创 [LeetCode]Interleaving String
Given s1, s2, s3, find whether s3 is formed by the interleaving of s1 and s2.For example,Given:s1 = "aabcc",s2 = "dbbca",When s3 = "aadbbcbcac", return true.When s3 = "aadbbbaccc", r
2015-12-26 14:29:19
288
原创 [LeetCode]Scramble String
Given a string s1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively.Below is one possible representation of s1 = "great": great / \ gr
2015-12-26 14:19:51
356
原创 [LeetCode]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
2015-12-19 20:47:47
364
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