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

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&

This document summarizes key concepts and solutions from previous database exam questions.

Relational Schema with Functional Dependencies

• Schema: R(A, B, C, D, E, F)
• Dependencies: C → F, E → A, EC → D, A → B

1. Candidate Keys: CE
2. Prime Attributes: C, E
3. Second Normal Form (2NF):
   • No, because of partial dependencies:
     • C → F (partial dependency)
     • E → A, B (partial dependency)

EMP_DEPT Table Analysis

1. Functional Dependencies:
   • Ssn → Ename, Bdate, Address, Dnumber, Dname, Dmgr_ssn
   • Dnumber → Dname, Dmgr_ssn
   • Dmgr_ssn → Dnumber, Dname
   • Dname → Dnumber, Dmgr_ssn
2. First Normal Form (1NF):
   • Split names into first_name and last_name.
3. Second Normal Form (2NF):
   • Already in 2NF because there are no partial dependencies.

EMP_PROJ Table Normalization

1. Functional Dependencies:

React Hooks and Essential Libraries

useState Hook

Purpose

Purpose: Adds state to functional components.

Import

import { useState } from 'react';

Syntax

const [state, setState] = useState(initialValue);

Update Methods

• setState(newValue);
• setState(prevState => ...); (for updates based on previous state)

Example

import React, { useState } from 'react';

function Counter() {
  const [count, setCount] = useState(0);

  return (
    <div>
      <p>Count: {count}</p>
      <button onClick={() => setCount(count + 1)}>Increment</button>
    </div>
  );
}

useEffect Hook

Purpose

Purpose: Performs side effects such as data fetching, subscriptions, or direct DOM manipulations.

Import

import { useEffect } from 'react';

Syntax

useEffect(

Input three numbers and find the largest. Enter a number and display the day name of the week.
#include
#include
using namespace std;
using namespace std;
int main() {
int num1, num2, num3;
int day;
cout << "Enter three numbers: ";
cout << "Enter a number (From 1 to 7): ";
cin >> num1 >> num2 >> num3;
cin >> day;
if (num1 > num2 && num1 > num3) {
cout << "Largest number is " << num1;
} else if (num2 > num3) {
cout << "Largest number is " << num2;
} else {
cout << "Largest number is " << num3;
}
switch (day) {
case 1: cout << "Sunday"; break;
case 2: cout << "Monday"; break;
... Continue reading "Find the Largest Number and Calculate Factorial in C++" »