Detailed explanation of Redis caching problems

cache penetrationCache penetration means that the data requested by the client does not exist in the cache and the database, so the cache will never take effect, and these requests will hit the databaseIf a malicious user uses countless threads to concurrently access non-existent data, these requests will all reach the database, which is likely ...

Posted by bliss322 on Sun, 25 Sep 2022 21:01:59 +0300

Implementation of Common Sorting Algorithms (Java Version)

Common sorting algorithms 1, Select Sort Selective sorting is a simple and intuitive sorting algorithm 1. First, find the smallest (large) element in the unsorted sequence and store it at the beginning of the sorted sequence.2. Then continue to find the smallest (largest) element from the remaining unsorted elements, and then put it at the e ...

Posted by Clukey on Sat, 24 Sep 2022 21:46:56 +0300

dp14-17 longest ascending subsequence - original title + variant

dp 14 longest ascending subsequence (1) Topic description describe Given an array arr of length n, find the length of its longest strictly ascending subsequence. The so-called subsequence refers to a new array formed by deleting some numbers (or not deleting) from an array. For example [1,5,3,7,3] array, its subsequences are: [1,3,3], [ ...

Posted by cheese on Fri, 23 Sep 2022 21:58:32 +0300

CF Round 812 F. Lost Array

F. Lost Array I spent many hours fooling around yesterday, reading the wrong questions and reading the wrong code. Finally, I got out of the mess. I wrote a blog to record the mentality of nearly breaking the computer yesterday Observe the mysterious code of others and find the following mysterious properties For ordered column subset XOR, ...

Posted by Sillysoft on Thu, 15 Sep 2022 21:16:40 +0300

word memory system

Topic B4: Keyword-based text sorting and retrieval system 1. Subject content and requirements Topic B4: (1) Subject content "Memorizing words - personalized memorizing words" is a software for reciting English words. Users can import the thesaurus to be recited according to their own needs, and can edit their own thesaurus. There a ...

Posted by john-formby on Sun, 11 Sep 2022 21:29:45 +0300

birthday cake question

A problem description Make a birthday cake of volume Nπ with M layers, each layer being a cylinder. Suppose the i-th layer of cake from bottom to top is a cylinder with radius Ri and height Hi. When I < m, RI > RI + 1 and hi > hi + 1. Since the cake maker needs to spread the cream, in order to save money as much as possible, it i ...

Posted by El_Dudereno on Thu, 08 Sep 2022 21:08:15 +0300

Derivation of C++ decltype type

decltype specifier (C++11) C++11 introduces a decltype specifier, which can obtain the type of an object or expression. It is also easy to use: #include <iostream> int main() { int x1 = 0; decltype(x1) x2 = 0; // x2 is derived as int type (type of variable x1) std::cout << typeid(x2).name() << s ...

Posted by bimbo on Wed, 07 Sep 2022 22:08:45 +0300

ReentrantLock lock related methods

catalogue Implementation class of Lock interface ReentrantLock method ReentrantLockTest test Thread for testing t1 test Release the reentry lock correctly Get the current number of reentries t1t2 test Use the islocked() method to detect the lock state t1t3 test Use the trylock method to attempt to acquire a lock U ...

Posted by wxflint on Sun, 04 Sep 2022 22:34:19 +0300

Notes on interfaces, polymorphism, inner classes, and more!

1. Static The static keyword can modify member variables and member methods basic concept: static member belongs to class It can be accessed through the class name, and is generally modified with public classname.propertyname; classname.methodname(); can also be accessed by object name (not recommended) Memory explanation: Sta ...

Posted by ess14 on Wed, 31 Aug 2022 03:28:19 +0300

python loop keywords and lists

1, Nested loop comparison (code runtime management) In python, if we want to pursue the simplicity of the code, we need to understand that more code will take more time to run, which will reduce the work efficiency. Next, we observe the effect through python's time library import time start=time.time() for x in range(0, 35): # y stan ...

Posted by paulsiew2 on Fri, 26 Aug 2022 00:29:49 +0300