Notes, abstracts, papers, exams and problems of Computers

What is an Exception?

Answer: An exception in Python is an error that occurs during program execution, disrupting the normal flow of instructions. Instead of crashing, the program can "catch" the exception and handle it gracefully using try and except blocks. Common exceptions include ZeroDivisionError, IndexError, and FileNotFoundError. You can also define custom exceptions. The finally block can be used for cleanup actions, ensuring certain code runs regardless of whether an exception was raised.

Different Modes of Opening a File

Answer: Different Modes of Opening a File

1. Read Mode ('r')

• Purpose: Opens a file for reading.
• Behavior:
  • The file pointer is placed at the beginning of the file.
  • If the file does not exist, a FileNotFoundError is raised.

C Programming Examples

Here are several C programming examples:

Vector Operations

#include <stdio.h>

void leVetor (int v [] , int tam );
int prodEscalar (int v1 [] , int v2 [] , int tam );

int main (void) {
    int v1 [ DIM ], int v2 [ DIM ];
    int i;
    int prod ;

    leVetor (v1 , DIM );
    leVetor (v2 , DIM );
    prod = prodEscalar (v1 , v2 , DIM );
    printf ("%d\n", prod );
    return 0;
}

void leVetor (int v [] , int tam ) {
    /* Completar */
}

int prodEscalar (int v1 [] , int v2 [] , int tam ) {
    /* Completar */
}

Random Number Generation

#include <stdio.h>
#include <time.h>
#include <stdlib.h>

#define VEZES 10

int main (void) {
    int i , j , k;
    double r;

    srand ( time ( NULL )); /* inicializa

Button Click Action Events

import java.awt.*;

import java.awt.event.*;

public class ButtonClickActionEvents

{

public static void main(String args[])

{

Frame f=new Frame("Button Event");

Label l=new Label("DETAILS OF PARENTS");

l.setFont(new Font("Calibri",Font.BOLD, 16));

Label nl=new Label();

Label dl=new Label();

Label al=new Label();

l.setBounds(20,20,500,50);

nl.setBounds(20,110,500,30);

dl.setBounds(20,150,500,30);

al.setBounds(20,190,500,30);

Button mb=new Button("Mother");

mb.setBounds(20,70,50,30);

mb.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

nl.setText("NAME: " + "Aishwarya");

dl.setText("DESIGNATION: " + "Professor");

al.setText("AGE: " + "42");

}

});

Button fb=new Button("Father");

fb.setBounds(80,70,50,30);

fb.addActionListener(

Tokens

In programming, a token is the smallest meaningful element in code. They are the building blocks of a language's syntax. Common token types include:

• Keywords: Reserved words like if, else, while, and int (for declaring integers).
• Identifiers: Names given to elements like variables (e.g., sum), functions, and arrays.
• Constants: Unchanging values during program execution (e.g., 3.14 for pi).
• Operators: Symbols for mathematical or logical operations (e.g., + for addition).
• Separators: Punctuation like commas (,), semicolons (;), and braces ({}).

Example: int sum = 10 + 5;

In this line, int is a keyword, sum is an identifier, = is an operator, 10 and 5 are constants, and ; is a separator.

Arithmetic Operators

C has nine arithmetic operators for basic... Continue reading "C Programming: Tokens, Operators, and Logic" »

Dijkstra's Algorithm in C

This code implements Dijkstra's algorithm to find the shortest path from a source vertex to all other vertices in a graph represented as an adjacency matrix. The program reads graph data from an input.txt file and writes the results to an output.txt file.

Code Implementation

#include <stdio.h>
#include <limits.h>
#include <stdbool.h>

#define MAX_VERTICES 100

// Function to find the vertex with minimum distance
int minDistance(int dist[], bool visited[], int vertices) {
    int min = INT_MAX, min_index;

    for (int v = 0; v < vertices; v++)
        if (!visited[v] && dist[v] <= min) {
            min = dist[v];
            min_index = v;
        }

    return min_index;
}

// Dijkstra'

Binary Parallel Adder

A binary parallel adder is a digital circuit that adds two binary numbers in parallel, meaning all bits are added simultaneously. It typically consists of full adders arranged in parallel, with each full adder adding corresponding bits from the two input numbers.

BCD Adder

A BCD (Binary Coded Decimal) adder is a specific type of binary parallel adder designed to add two BCD numbers. BCD numbers are decimal digits encoded in binary, where each decimal digit is represented by its 4-bit binary equivalent.

Truth Table for a 4-bit BCD Adder

Here's the truth table for a 4-bit BCD adder:

Diagram

In the truth table:

• A3 A2 A1 A0 represents the first BCD number (A).
• B3 B2 B1 B0 represents the second BCD number (B).
• Cin represents the carry-

Essential Algorithms and Data Structures

Longest Increasing Subsequence (LIS):

• Subproblem: dp[i] = length of LIS ending at index i
• Recursion: dp[i] = max(dp[j] + 1 for j < i and arr[j] < arr[i])
• Base case: dp[i] = 1 (every element is a subsequence of length 1)
• Time Complexity: O(n^2), O(n log n) with binary search optimization.

Longest Alternating Subsequence (LAS):

• Subproblem: dp[i][0] (increasing), dp[i][1] (decreasing)
• Recursion: dp[i][0] = max(dp[j][1] + 1 for j < i and arr[j] < arr[i]), dp[i][1] = max(dp[j][0] + 1 for j < i and arr[j] > arr[i])
• Base case: dp[0][0] = 1, dp[0][1] = 1
• Time Complexity: O(n^2)

0/1 Knapsack Problem:

• Subproblem: dp[i][w] = maximum value for the first i items and weight limit w
• Recursion: dp[i][w] = max(

Arithmetic Mean

The following C++ code calculates the arithmetic mean of numbers from 1 to n:

int main() {
    int n;
    double suma = 0;
    cout << "Vnesi broj: ";
    cin >> n;
    if (n <= 0) {
        cout << "Brojot na elementi mora da bide pogolem od 0!" << endl;
        return 1;  
    }
    for (int i = 1; i <= n; i++) {
        suma += i;  
    }
    double sredina = suma / n;
    cout << "Aritmetichkata sredina na broevite od 1 do " << n << " e: " << sredina << endl;
    return 0;
}

Sum

The following C++ code calculates the sum of numbers from 1 to n:

int main() {
    int n, sum = 0;
    cout << "Vnesi broj n: ";
    cin >> n;
    for (int i = 1; i <= n; i++)