A simplified main program used to test functions is called

Let S be the set of all strings from A* in which there is no b before an a. For example, the strings λ, aa, bbb, and aabbbb all

alexdok [17]

Answer:

Check the explanation

Explanation:

A recurvsive defintion for $A^{*}$ which contains all possible strings over the alphabet $A=\{a,b\}$ is \lambda\in $A^*$ (contains the null strings) and $A^{*}=\{uv:u\in A^*,v\in A\}$

A recurvsive defintion for $A^{+}$ which contains all possible strings over the alphabet $A=\{a,b\}$ is $a,b\in$ $A^+$ (contains the strings of lengths 1) and $A^{+}=\{uv:u\in A^+,v\in A\}$

$c) \lambda \in S and$

$w\in S\Rightarrow wb \in S$

$bw\in S\Rightarrow baw \in S$ and $awb\in S$

is the required recursive definition for S

For example, $a\in S and from w\in S\Rightarrow wa\in S\text{ we get }aa\in S$ also

Again, as $ab\in S$ and from $wb\in S\Rightarrow wab \in S we get aab\in S$

And as $aab\in S,$ from $wb\in S\Rightarrow wab \in S and awb\in S$ we have $aaab\in S$

3 0

2 years ago

In this assignment you'll write a program that encrypts the alphabetic letters in a file using the Vigenère cipher. Your program

solniwko [45]

Answer:

C code is given below

Explanation:

// Vigenere cipher

#include <ctype.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

/**

* Reading key file.

*/

char *readFile(char *fileName) {

FILE *file = fopen(fileName, "r");

char *code;

size_t n = 0;

int c;

if (file == NULL) return NULL; //could not open file

code = (char *)malloc(513);

while ((c = fgetc(file)) != EOF) {

if( !isalpha(c) )

continue;

if( isupper(c) )

c = tolower(c);

code[n++] = (char)c;

}

code[n] = '\0';

fclose(file);

return code;

}

int main(int argc, char ** argv){

// Check if correct # of arguments given

if (argc != 3) {

printf("Wrong number of arguments. Please try again.\n");

return 1;

}

// try to read the key file

char *key = readFile(argv[1]);

if( !key ) {

printf( "Invalid file %s\n", argv[1] );

return 1;

}

char *data = readFile(argv[2]);

if( !data ) {

printf("Invalid file %s\n", argv[2] );

return 1;

}

// Store key as string and get length

int kLen = strlen(key);

int dataLen = strlen( data );

printf("%s\n", key );

printf("%s\n", data );

int paddingLength = dataLen % kLen;

if( kLen > dataLen ) {

paddingLength = kLen - dataLen;

}

for( int i = 0; i < paddingLength && dataLen + paddingLength <= 512; i++ ) {

data[ dataLen + i ] = 'x';

}

dataLen += paddingLength;

// Loop through text

for (int i = 0, j = 0, n = dataLen; i < n; i++) {

// Get key for this letter

int letterKey = tolower(key[j % kLen]) - 'a';

// Keep case of letter

if (isupper(data[i])) {

// Get modulo number and add to appropriate case

printf("%c", 'A' + (data[i] - 'A' + letterKey) % 26);

// Only increment j when used

j++;

}

else if (islower(data[i])) {

printf("%c", 'a' + (data[i] - 'a' + letterKey) % 26);

j++;

}

else {

// return unchanged

printf("%c", data[i]);

}

if( (i+1) % 80 == 0 ) {

printf("\n");

}

printf("\n");

return 0;

}

4 0

2 years ago

Read 2 more answers

Checkpoint 7.61 Write the prototype for a function named showSeatingChart that will accept the following two-dimensional array a

Kobotan [32]

Answer:

void showSeatingChart(const string [][COLS], int);

Explanation:

void showSeatingChart(const string [][COLS], int);

The above function showSeatingChart() will display the 2D array of seating chart.

The return type of this function is void because it does not need to retun anything.

The parameter of the function is a 2D array which is seatingChart[ROWS][COLS].

The type of this 2D array is string that means it is a 2D array of string. It will contain string elements.

To declare a prototype of a function, there should be a semi-colon (;) at the end of declaration.

The definition of the function should be given outside main() function and declaration of the function should be above the main() function or at the beginning of the program with declaration of constant variables.

7 0

2 years ago

Read 2 more answers

Assume that a boolean variable workedOvertime has been declared, and that another variable, hoursWorked has been declared and in

meriva

Answer:

The c++ program to show the use of Boolean variable is given below.

#include <iostream>

using namespace std;

int main() {

int hoursWorked = 44;

bool workedOvertime;

cout<<"This program shows the use of boolean variable." <<endl;

// overtime refers to working hours more than 40 hours

if(hoursWorked > 40)

{

workedOvertime = true;

cout<<"The value of boolean variable workedOvertime is true or "<<workedOvertime<<endl;

}

// if working hours are less than or equal to 40, overtime is not considered

else

{

workedOvertime = false;

cout<<"The value of boolean variable workedOvertime is false or "<<workedOvertime<<endl;

}

return 0;

}

OUTPUT

This program shows the use of boolean variable.

The value of boolean variable workedOvertime is true or 1

Explanation:

This program uses a boolean variable to indicate the overtime of working hours.

The boolean variable is declared as shown.

bool workedOvertime;

The working hours is stored in an integer variable which is declared and initialized within the program itself.

int hoursWorked = 44;

Depending on the value of working hours, the boolean variable is assigned the value true or false.

if(hoursWorked > 40)

{

workedOvertime = true;

cout<<"The value of boolean variable workedOvertime is true or "<<workedOvertime<<endl;

}

else

{

workedOvertime = false;

cout<<"The value of boolean variable workedOvertime is false or "<<workedOvertime<<endl;

}

The value of boolean variable is displayed to the user.

In the above program, the working hours are 44 which is more than normal working hours of 40. Hence, boolean variable is assigned value true.

This program does not accept user input for working hours as stated in the question. Since value of working hours is not accepted from the user, there is no logic implemented to check the validity of the input.

This program can be tested for different values of working hours to test for the boolean variable.

8 0

2 years ago

Given a sorted array of integer, A, with possible duplicate elements. Implement an efficient (sublinear running time complexity)

allsm [11]

Answer:

The java program is as follows.

import java.util.*;

import java.lang.*;

public class SearchProgram

{

// sorted array may or may not containing duplicate elements

static int A[] = {-1, 2, 3, 5, 6, 6, 6, 9, 10};

// variable to keep track of number of occurrences, declared and initialized to 0

static int times=0;

// variable to hold value to be searched in the array

static int key;

static int search(int[] art, int n)

{

// enhanced for loop used to find how many times n occurs in array, arr

for(int j:arr)

{

if(n == j)

times = times+1;

}

return times;

}

public static void main(String[] args)

{

// scanner object to allow user input

Scanner sc = new Scanner(System.in);

// user prompted to enter key to be searched

System.out.print("Enter the element to be searched: ");

key = sc.nextInt();

// message displayed to the user on how many times the element is present in the array

System.out.println("The element " + key + " is present " + search(A, key) + " times in the array.");

}

OUTPUT

Enter the element to be searched: 3

The element 3 is present 1 times in the array.

Explanation:

The steps of program execution are shown below.

1. An integer array, A, is declared and initialized.

2. An integer variable, times, is declared and initialized to 0.

3. A method, search(), is created which takes 2 parameters, array A and user entered value for the element to be searched in A.

4. The search() method has return type of integer and returns the value of variable, times.

5. Inside the search() method, an enhanced for loop is used to compute the value of the variable, times.

6. In the main() method, user is prompted to enter the value of key.

7. The search() is called and value of the variable, times, displayed to the user.

8. All the methods and variables are declared as static.

7 0

2 years ago