Stack implementation synthesis calculator (infix expression)
We need two stacks: number stack and symbol stack to define an index index index index to traverse the expression
Traverse to a number, then enter the number stack
Traverse to a symbol. If the symbol stack is empty, it wil ...
Added by cags on Sun, 21 Jun 2020 08:37:34 +0300
Input an increasing sort array and a number S, find two numbers in the array, make their sum S, and output any pair.
Seeing this problem, the simplest way we can think of is to fix a number first, and then judge whether the sum of n - 1 numbers is S, but the time complexity is O(n^2).
You can ...
Added by installer69 on Sat, 20 Jun 2020 12:13:26 +0300
1. Biscuit distribution (NO.455)
Title Description: suppose you are a great parent and want to give your children some cookies. However, each child can only be given one cookie at most. For each child i, there is an appetite value gi, which is the minimum size of biscuits that can satisfy the children ...
Added by ViN86 on Fri, 19 Jun 2020 12:58:06 +0300
Here, we will introduce and explain the feature data selection methods often used in Feature Engineering, which are divided into three parts: single variable selection, linear model selection and random forest model feature selection.
Trilogy 1: single variable selection
For data scientists or m ...
Added by Yari on Fri, 19 Jun 2020 11:42:14 +0300
It's easy to think that the question is related to Steiner tree.
So let's suppose that f(i,sta)f(i,sta)f(i,sta) denotes the minimum cost when the root is iii and the state of pressure at the key point is sta stastasta.
Then all f(i,sta)f(i,sta)f(i,sta) can be found by using the template of Steiner tree. ...
Added by feign3 on Thu, 18 Jun 2020 09:13:08 +0300
DQL data query language
Equivalence / connection query
Omit connection conditions
Invalid connection condition
All rows in all tables are connec ...
Added by nocniagenti on Thu, 18 Jun 2020 08:26:10 +0300
Introduction to NFS
NFS is network Short for file system, the main function is to let different machines and different operating systems share the specified resource files with each other through the network. It can be simply considered as a ...
Added by rhaggert on Wed, 17 Jun 2020 07:47:11 +0300
Reference video: Start Python data mining in 4 days
1 Numpy advantage
1.1 introduction to numpy
Numpy (Numerical Python) is an open-source Python science computing library, which is used to quickly process arrays of any dimension. (numerical → \ to → numerical)
Numpy supports common arr ...
Added by AnarKy on Tue, 16 Jun 2020 09:31:42 +0300
QuerySet API usage
QuerySet can construct, filter, slice, and approximate results without actually accessing the database. Unless you do something to evaluate the query set, no query activity actually occurs to the database.
(1) Basic properties
The QuerySet is iterative, and its databa ...
Added by Phire on Tue, 16 Jun 2020 06:59:36 +0300
Use Redis command action
Working with Java code
The Principle and Feature of HyperLog Implementation
Implement HyperLog using Java
Web site UV refers to the amount of Unique Visitor visited by independent users of a Web site, that ...
Added by BlueSkyIS on Tue, 16 Jun 2020 03:56:18 +0300