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Algorithms, Distributed System, Machine Learning
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05 2015 档案

LeetCode "Contains Duplicate II"
摘要：Maintain a hashset with size of (K + 1)class Solution {public: bool containsNearbyDuplicate(vector& nums, int k) { unordered_set hs; ... 阅读全文
posted @ 2015-05-30 01:36 Tonix 阅读(157) 评论(0) 推荐(0)

LeetCode "The Skyline Problem"
摘要：Good one. My first reaction to this problem is the same idea as this answer:https://leetcode.com/discuss/37365/accepted-c-solution-o-nlogn-using-maxhe... 阅读全文
posted @ 2015-05-29 01:44 Tonix 阅读(393) 评论(0) 推荐(0)

HackerRank - "Identify Smith Numbers"
摘要：I guess the punch line of this one is Sieving for primes.#include #include #include #include #include #include #include #include using namespace std;v... 阅读全文
posted @ 2015-05-28 01:48 Tonix 阅读(260) 评论(0) 推荐(0)

HackerRank - "Chief Hopper"
摘要：Apparently it is by a backwards derivation solution. Say energy at h[i] is e, the next energy at h[i+1] is 2*e - h[i+1] => e', so backwards, e = ceil(... 阅读全文
posted @ 2015-05-27 07:03 Tonix 阅读(261) 评论(0) 推荐(0)

HackerRank - "Two arrays"
摘要：We match larger in array_a with smaller in array_b, by which we can have as even sum as possible, so we don't have too small sums.#include #include #i... 阅读全文
posted @ 2015-05-27 00:44 Tonix 阅读(139) 评论(0) 推荐(0)

HackerRank - "Flowers"
摘要：Apparently, more expensive flowers should be bought with lower coeff. (Greedy part), and any unbalanced assignment would cause extra cost.So the code ... 阅读全文
posted @ 2015-05-26 14:16 Tonix 阅读(151) 评论(0) 推荐(0)

LeetCode "Combination Sum III"
摘要：Typical recursion usage.class Solution { vector> ret; void dfs(vector curr, int currSum, int maxN, int n, int k) { // Ending ... 阅读全文
posted @ 2015-05-25 15:14 Tonix 阅读(233) 评论(0) 推荐(0)

LeetCode "Shortest Palindrome"
摘要：To have "shortest" expanded palindrome, we should know the longest "heading" palindrome in original string, so that we can reuse as much part as possi... 阅读全文
posted @ 2015-05-23 02:17 Tonix 阅读(249) 评论(0) 推荐(0)

HackerRank - "Maximise Sum"
摘要：It is modulo version of "max sum of contiguous subarray". So similar pattern can be applied too, but with tricks regarding to modulo ops.I checked edi... 阅读全文
posted @ 2015-05-22 14:19 Tonix 阅读(653) 评论(0) 推荐(0)

HackerRank - "Triplets"
摘要：Good one to learn Binary Indexed Tree (Fenwick Tree). Simply grabbed the editorial's code but with comments.#include #include #include #include #inclu... 阅读全文
posted @ 2015-05-21 07:34 Tonix 阅读(276) 评论(0) 推荐(0)

LeetCode "House Robber II"
摘要：A high quality DP problem to work on. It is not an merely educational DP, it is subtle.Basic ideas: 1. Run original DP twice, 1st with num[0] selecte... 阅读全文
posted @ 2015-05-20 11:00 Tonix 阅读(439) 评论(0) 推荐(0)

LeetCode "Word Search II"
摘要：Trie, again.class TrieNode {public: // Initialize your data structure here. TrieNode() : prev(nullptr), c(0), bIsLast(false) { } TrieNo... 阅读全文
posted @ 2015-05-20 04:32 Tonix 阅读(192) 评论(0) 推荐(0)

LeetCode "Add and Search Word - Data structure design"
摘要：I'm glad to see that LeetCode has finally realized the importance of Trie.My C++ code can be further optimized..class TrieNode {public: // Initiali... 阅读全文
posted @ 2015-05-20 01:28 Tonix 阅读(262) 评论(0) 推荐(0)

HackerRank - "String Modification"
摘要：An ACM-level problem because it involves "advanced maths". It should not be marked as "Moderate". Other than that, it is a medium level DP one.*Math m... 阅读全文
posted @ 2015-05-19 10:53 Tonix 阅读(268) 评论(0) 推荐(0)

HackerRank - "Coin on the Table" - 3D DP
摘要：This is my 1st 3D DP problem, and it should be an educational one. But, still tricky to me.Here is a good article:http://www.cnblogs.com/sunshineatnoo... 阅读全文
posted @ 2015-05-15 15:49 Tonix 阅读(253) 评论(0) 推荐(0)

Hey... I have different view on training algorithm now
摘要：Basically speaking, I got higher resolution view into code now, in a 庖丁解牛 style. Previously, I treated one program as a whole, and sometimes I got con... 阅读全文
posted @ 2015-05-15 03:28 Tonix 阅读(111) 评论(0) 推荐(0)

LeetCode "Course Schedule II"
摘要：This one lets you print out one topological sorted sequence. Either BFS or DFS works. But there are tricky details.This is my reference:https://leetco... 阅读全文
posted @ 2015-05-15 02:46 Tonix 阅读(217) 评论(0) 推荐(0)

LeetCode "Mininum Size Subarray Sum"
摘要：O(n): Sliding window:class Solution {public: int minSubArrayLen(int s, vector& nums) { int len = nums.size(); if (len == 0) return... 阅读全文
posted @ 2015-05-13 15:43 Tonix 阅读(229) 评论(0) 推荐(0)

LeetCode "Course Schedule"
摘要：Topological sorting. This is my DFS solution. Please note that I used _rec to avoid duplicate checking.class Solution {public: map rec; set _rec... 阅读全文
posted @ 2015-05-13 14:37 Tonix 阅读(148) 评论(0) 推荐(0)

LeetCode "Implement Trie (Prefix Tree)"
摘要：Implementation problem.class TrieNode {public: // Initialize your data structure here. TrieNode() { c = 0; bIsLast = false; } ... 阅读全文
posted @ 2015-05-13 13:28 Tonix 阅读(266) 评论(0) 推荐(0)

HackerRank - Number List
摘要：Solution 1:https://www.hackerrank.com/challenges/number-list/editorialReversed thought: total no. of subsets - no. of subsets without arr[i] > kSoluti... 阅读全文
posted @ 2015-05-11 05:08 Tonix 阅读(185) 评论(0) 推荐(0)

HackerRank - Find Maximum Index Product
摘要：I treated it too difficult.. nothing special, just some optimization mentioned as:http://saraguru.weebly.com/how-i-solved/find-maximum-index-product-h... 阅读全文
posted @ 2015-05-10 14:12 Tonix 阅读(439) 评论(0) 推荐(0)

HackerRank - "The Longest Increasing Subsequence"
摘要：It requires O(nlgn) solution. And actually I think the passing code is for "non-decreasing"..#include #include #include #include #include #include #in... 阅读全文
posted @ 2015-05-10 12:30 Tonix 阅读(219) 评论(0) 推荐(0)

HackerRank - Substring Diff
摘要：Really interesting problem. Naive solution would be O(n^3). But please note the pattern here: (i, j, k) -> (i + 1, j + 1, k) -> (i + 2, j + 2, k)... t... 阅读全文
posted @ 2015-05-08 07:23 Tonix 阅读(465) 评论(0) 推荐(0)

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