Notes, summaries, assignments, exams, and problems for Computers

Understanding Variables & Data Types

Variables: Storing Data

Variables are containers used to store data. They are assigned values using the = operator (e.g., x = 5).

Essential Data Types

Python supports several fundamental data types:

• int: Represents integer numbers (e.g., 10, -5).
• float: Represents floating-point numbers (e.g., 3.14, -0.01).
• str: Represents strings of characters (e.g., "hello", "123").
• bool: Represents Boolean values, either True or False.

Type Casting: Converting Data Types

Type casting allows you to convert data from one type to another using functions like int(), float(), and str().

Example: x = int("5") converts the string "5" to an integer. y = float("3.14") converts the string "3.14" to a float.

Input and Output Operations

Getting

C printf Function: Format Specifiers Explained

The printf function in C is used to display formatted output to the standard output (usually the console). It allows programmers to control how data is presented by using **format specifiers**. Format specifiers are placeholders that define the type of data being printed and how it should be formatted. They begin with a % symbol, followed by a character that specifies the data type.

Role of Format Specifiers

Format specifiers serve two main purposes:

1. Data Type Identification: They inform the printf function about the type of data being passed as an argument. For example, %d is used for integers, while %f is used for floating-point numbers.
2. Formatting Control: They allow customization of how the data

1)A virtual-circuit network (VCN) is a hybrid network model that combines features of both circuit-switched and datagram networks. It provides a balance between connection-oriented and connectionless transmission methods :-Three Phases in a Virtual-Circuit Network In a virtual-circuit network, the communication between a source and destination involves three phases: setup, data transfer, and teardown. These phases ensure that a reliable path is established and maintained for the communication session. 1. Setup Phase: o The source and destination use their global addresses to establish a connection. During this phase, switches along the path create table entries to store information about the virtual circuit. This phase ensures that each switch... Continue reading "Core Concepts in Network Layer Protocols and Routing" »

Linux File System Structure: An archive of Linux is associated with 3 parts: superblock, inode table, and data blocks.

Network Ports: To see the ports assigned to services.

Display Active TCP/IP Connections: netstat -a

User Management:

• Create password: passwd (user)
• Add user to group: usermod -g group_name
• Disable: 60001
• Enable: 60002

Practical Commands:

Add User: adduser

1. Change folder privileges: chmod
2. Check privileges: ls -de (see if you changed privileges)

1. Create a user: useradd newuser
passwd newuser
2. Create a directory: The command mkdir is used to create directories:
   mkdir mydirectory
3. Create a report: ps -aux >> reporte.txt
4. Directories associated with the user: -d dirname
5. Changing permission: chmod 744 file.txt /file.txt
6. Change owner: chown
   Entering

############################### lAB 9 ####################3
import gymnasium as gym
import numpy as np
import tensorflow as tf

# Create the environment
env = gym.Make("CartPole-v1")

# Define a simple neural network model for the policy
model = tf.Keras.Sequential([
    tf.Keras.Layers.Dense(16, activation='relu', input_shape=(env.Observation_space.Shape[0],)),
    tf.Keras.Layers.Dense(env.Action_space.N, activation='softmax')
])

# Define the optimizer
optimizer = tf.Keras.Optimizers.Adam(learning_rate=0.01)

# Function to choose an action based on the current policy
def choose_action(state):
    """
    Chooses an action based on the probabilities output by the policy model.
    Args:
        state (np.Array): The current observation/state from... Continue reading "Implementing REINFORCE Policy Gradient for CartPole-v1" »

Internet vs. World Wide Web (WWW)

• Internet: A global network infrastructure that uses TCP/IP to connect devices worldwide.
• WWW (World Wide Web): A multimedia service built upon the Internet, utilizing HTML, CSS, web browsers, and hyperlinks.
• Webpage: A single document accessible via the WWW. | Website: A collection or group of related webpages.

History and Evolution of the Internet

• 1960s: Development of ARPANET (Advanced Research Projects Agency Network).
• 1983: Adoption of the TCP/IP protocol suite (developed by Vint Cerf and Bob Kahn).
• 1989: Invention of the World Wide Web (WWW) by Tim Berners-Lee.
• 1992: Release of the Mosaic browser (developed at UIUC), popularizing the graphical web.

Understanding the Client-Server Model

• Client: Initiates a request

Ejercicio de descuentos:

#!/bin/bash

read -p "¿Desea el billete también de vuelta? (s/n): " idavuelta

until [ $idavuelta=="s" ] || [ $idavuelta=="n" ]; do

read -p "¿Desea el billete también de vuelta? (s/n): " idavuelta

done

read -p "¿Tiene carnet joven? (s/n): " carnetjoven

until [ $carnetjoven="s" ] || [ $carnetjoven="n" ]; do

read -p "¿Tiene carnet joven? (s/n): " carnetjoven

done

descuento=0 billete=20

if [ $idavuelta="s" ]; then

descuento=20

billete=" expr $billete \* 2'

fi

if [ $carnetjoven="s" ]j then

descuento=30

fi

costefinal=`expr $billete \* \( 100 - $descuento \) / 100`

echo "El precio final del billete es $costefinal"

Ejercicio de medias:

#!/bin/bash

acu=0

cont=0

read -p "Introduce un numero: " num

while [ $num -ne 0 ]; do

acu=`expr $acu + $num`

cont=... Continue reading "Shell script" »

Jose Andres Gutierrez Vargas

Email: [email protected]
Phone: [Your Phone Number]

Professional Summary

Results-driven and highly motivated Software Developer with extensive expertise in backend and frontend development, RESTful APIs, and database management. Skilled in SQL and NoSQL databases, with in-depth experience in Node.js for building scalable and high-performance applications. Adept at optimizing system performance, troubleshooting technical issues, and implementing innovative solutions.

Former Frontend Developer at Google, where I contributed to the development of dynamic and interactive web applications, enhancing user experiences through cutting-edge technologies. Passionate about software development, staying updated with the latest... Continue reading "Jose Andres Gutierrez Vargas: Software Developer Profile" »

Problem Statement 16: Coin Change

Given a set of coins and a value, find the minimum number of coins to satisfy the given value.

Test Case 1:

Coins: {25, 20, 10, 5}, Value: 50 cents

Used coin: 25 cents

Used coin: 25 cents

Total number of coins: 2

Test Case 2:

Coins: {25, 20, 10, 5}, Value: 73 cents

Used coin: 25 cents

Used coin: 25 cents

Used coin: 20 cents

Used coin: 3 cents

Total number of coins: 4

Code:

-
#include int main { int amount =
50; int coins[] = {25, 20, 10, 5}; int
numCoins = 0;
printf("Amount: %d cents\n", amount);
for (int i = 0; i while (amount >= coins[i]){
amount -= coins 1;
numCoins++；
printf("Used
coin: %d cents\n", coins[i]);
}
printf("Total number of coins: %din", numCoins); return 0; }

Problem Statement 19: -#include #include int i,j,k,... Continue reading "C Programming Algorithms: Coin Change, Knapsack, MST, Shortest Path" »

Hexadecimal Integer Grammar Analysis

Consider the following grammar for hexadecimal integers:

• <hex literal> ::= 0x<number>
• <number> ::= <number><number> | <digit>
• <digit> ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F

The string 0xF3 is an element of the language generated by this grammar.

Derivation Sequences and Parse Trees

1. How many distinct derivation sequences exist for this string?

There exist 6 distinct derivation sequences:

• <hex literal> ⇒ 0x<number> ⇒ 0x<number><number> ⇒ 0x<digit><number> ⇒ 0x<digit><digit> ⇒ 0xF<digit> ⇒ 0xF3
• <hex literal> ⇒ 0x<number> ⇒ 0x<number><number> ⇒ 0x<number&