原创 lintcode: ugly number
問題描述 Ugly number is a number that only have factors 3, 5 and 7. Design an algorithm to find the Kth ugly number. Th
2020-02-21 05:33:56
原创 中序遍歷二叉樹+O(1)空間
問題描述 中序遍歷二叉樹時，很簡單，需要加上遞歸就可以優雅地實現了。當然，使用遞歸的話，函數調用棧的空間就會達到O(log n)。那麼有什麼方式，可以使得中序遍歷二叉樹的複雜度爲O(1)呢？ 問題分析 既然要保證O(1)複雜度，那
2020-02-21 05:33:56
原创 [Lintcode] Maximum Gap Problem
問題描述 在一個無序的數組中，如果對其進行排序，然後掃描一遍有序數組，可以獲得相鄰兩元素的最大差值，比如 {-1, 2, 4, 9}，那麼最大差值就是4和9之間，是5. 現在如果不對原始數組進行排序，有什麼好的方案，來獲取有序
2020-02-21 05:33:56
原创 【算法】直方圖中最大面積問題
問題描述 給定一個直方圖，求這個直方圖中最大矩陣對應的面積是多少？ 比如有個圖如下 （對應的數組爲：[2,1,5,6,2,3]） 那麼對應的最大矩形的面積應該爲 10： 問題分析 這類題是很常見的一道題，也是面試當中很容
2020-02-21 05:33:56
原创 [概率]m個球扔到n個盒子
問題描述 有m個球，要扔到n個盒子裏。其中每個球都是互相獨立地扔。問最後平均有幾個盒子是有球的？ 問題解析 這類問題是較爲純粹的數學問題，當然也可以用計算機精確地求出答案。 方案一：編程解決 p(m, i)：表示前 m 個球，扔
2020-02-21 05:33:56
原创 Timezone in Python
Just as a mark If we want to set PST timezone for a given datetime, it should be usually UTC-8. But sometimes it coul
2018-12-08 01:22:42
原创 debug date filter in logstash
Background Recently some guys came by and were curious about the date filter in logstash (both 2.4 and 5.x, but I am us
2018-08-22 04:50:15
原创 [Elasticsearch] setup Elasticsearch in intellij idea
Introduction Elasticsearch is quite a cool project. This post introduces how to setup Elasticsearch in IntelliJ Idea lo
2018-08-22 04:50:15
原创 Kibana aggregation with missing / null fields
Background Kibana is a good tool for aggregations. It looks like the group by in mysql. However Kibana will ignore docu
2018-08-22 04:50:15
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原创 Vim 多行替換
Replace multiple lines in Vim Aim // to replace the following line with new multiple lines // original line
2018-08-22 04:50:14
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原创 Kibana displays customized percentage in pie chart
Introduction Kibana 3 has got a good pie chart, which will displays the percentage label by default. But when it comes
2018-08-22 04:50:14
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原创 [Kibana > Timelion] Timelion.json is not working
Just a mark to investigate the reason configuration file of Timelion plugin is not working. It is maybe a designed feat
2018-08-22 04:50:13
原创 Java ObjectMapper String轉HashMap
Just to remind HashMap<String, Object> rDefHashMap = om.readValue(rDefStr, new TypeReference<HashMap<String, Object>>()
2018-08-22 04:50:13
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原创 [Kibana > Timelion] Divide multi-valued seriesList by another multi-valued seriesList
Kibana Timelion Plugin Enhancement Why need to divide multiple valued seriesList? Timelion is quite a great plugin for
2018-08-22 04:50:13
原创 Best time to buy and sell stocks IV
題目 https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iv/ Say you have an array for which the ith element i
2018-08-22 04:50:12
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