## Java shangsilicon Valley data structure and algorithm learning record

Stack implementation synthesis calculator (infix expression)
Thought analysis:
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*

## The two numbers of sword finger offer-41 and s -- and the continuous integer sequence of S

Topic 1
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*

## Classic topic of leetcode: greedy thoughts

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*

## Feature data selection Trilogy

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*

## [BZOJ4006] [JLOI2015] pipeline connection (Steiner tree)

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 2

DQL data query language
multi-table query
Cartesian set
Equivalence / connection query
join query
join link
Common functions
Subquery
Paging query
multi-table query
Cartesian set
Generation conditions:
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*

## Linux - NFS server summary

reference resources
http://cn.linux.vbird.org/linux_server/0330nfs.php#What_NFS_0
Introduction to NFS
introduce
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*

## numpy: a common module in python

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*

## django Series 5 - QuerySet API operation

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
iteration
The QuerySet is iterative, and its databa ...

Added by **Phire** on *Tue, 16 Jun 2020 06:59:36 +0300*

## Method of Using Redis to Count Web UV s

Article Directory
Preface
thinking
HyperLogLog
Use Redis command action
Working with Java code
The Principle and Feature of HyperLog Implementation
Implement HyperLog using Java
Summary
Preface
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*