Question

C Programming

// Compile with: clang radio.c -o radio

// Run with: ./radio

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <time.h>

// @Name    loadMusicFile

// @Brief   Load the music database

//          'size' is the size of the database.

char** loadMusicFile(const char* fileName, int size){

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

// Allocate memory for each character-string pointer

char** database = malloc(sizeof(char*)*size);

unsigned int song=0;

for(song =0; song < size; song++){

      // Allocate memory for each individual character string

      database[song] = malloc(sizeof(char)*80);

      // Copy over string

      database[song] = fgets(database[song],sizeof(char)*80,myFile);

}

// Import to always remember to close any file we open.

fclose(myFile);

// Return the pointer to our database

return database;

}

// @Name    printArrayOfCharStrings

// @Brief   Prints an array of C-style strings

void printArrayOfCharStrings(char** array, unsigned int start, unsigned int end){

int i;

for(i = start; i < end; i++){

    printf("[%d] %s",i,array[i]);

}

}

// @Name    swapStrings

// @Brief   Swaps two strings.

//          The lower string is put first

void swapStrings(char** s1, char** s2){

if( strcmp(*s1,*s2)==0 ){

    // Strings are identical, do nothing

    return;

}else if( strcmp(*s1,*s2) < 0 ){

    // Do nothing--we are already sorted

    return;

}else{

    char* temp = *s1;

    *s1 = *s2;

    *s2 = temp;

}

}

// @Name    bruteForceSort

// @Brief   A simple O(N*N) sorting algorithm.

void bruteForceSort(char** array, unsigned int start, unsigned int end){

    int i,j;

    for(i =start; i < end-1; i++){

        for(j =start; j < end-1; j++){

            // Note the swap here.

            swapStrings(&array[j],&array[j+1]);

        }

   }

}

// @Name    partition

// @Brief   Helper funcion for quicksort

int partition(char** array, unsigned int low, unsigned int high){

    // TODO:

}

void quicksort(char** array, unsigned int low, unsigned int high){

    // TODO:

}

int main(){

// Load our unsorted music file

// We load two copies, as we will compare two sorting algorithms.

char** musicDatabase1 = loadMusicFile("./musicdatabase.txt",13610);

char** musicDatabase2 = loadMusicFile("./musicdatabase.txt",13610);

// Print out a portion of the music database.

printf("The first 10 entries of 13609 unsorted are...\n");

printArrayOfCharStrings(musicDatabase1,0,10);

printf("\n");

// ===========================================

// ===== Experiment 1 - Using Brute Force Sort ====

// Create a clock to measure the elapsed time

clock_t start1,end1;

start1 = clock();

// perform bruteForceSort after starting your timer

bruteForceSort(musicDatabase1,0,13609);

end1 = clock();

double experiment1 = ((double)(end1-start1)/CLOCKS_PER_SEC);

   // ===========================================

  

// ===========================================

// ===== Experiment 2 - Using Quick Sort ====

//printArrayOfCharStrings(musicDatabase2,0,994);

// Create a clock to measure the elapsed time

clock_t start2,end2;

start2 = clock();

// perform quicksort after starting your timer

quicksort(musicDatabase2,0,13609);

end2 = clock();

double experiment2 = ((double)(end2-start2)/CLOCKS_PER_SEC);

// ===========================================

// check correctness

const int items = 10; // change this to up to 13609

printf("O(N*N) sort produces\n");

printArrayOfCharStrings(musicDatabase1,0,items);

printf("\n quick sort produces\n");

printArrayOfCharStrings(musicDatabase2,0,items);

// ============ Results ==============

printf("\nResults of sorting:\n");

printf("%f time taking for brute force\n", experiment1);

printf("%f time taking for quick sort\n", experiment2);

return 0;

}

Answer 1

Code :-

// Compile with: clang radio.c -o radio

// Run with: ./radio

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <time.h>

// @Name    loadMusicFile

// @Brief   Load the music database

//          'size' is the size of the database.

char** loadMusicFile(const char* fileName, int size){

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

// Allocate memory for each character-string pointer

char** database = malloc(sizeof(char*)*size);

unsigned int song=0;

for(song =0; song < size; song++){

      // Allocate memory for each individual character string

      database[song] = malloc(sizeof(char)*80);

      // Copy over string

      database[song] = fgets(database[song],sizeof(char)*80,myFile);

}

// Import to always remember to close any file we open.

fclose(myFile);

// Return the pointer to our database

return database;

}

// @Name    printArrayOfCharStrings

// @Brief   Prints an array of C-style strings

void printArrayOfCharStrings(char** array, unsigned int start, unsigned int end){

int i;

for(i = start; i < end; i++){

    printf("[%d] %s",i,array[i]);

}

}

// @Name    swapStrings

// @Brief   Swaps two strings.

//          The lower string is put first

void swapStrings(char** s1, char** s2){

if( strcmp(*s1,*s2)==0 ){

    // Strings are identical, do nothing

    return;

}else if( strcmp(*s1,*s2) < 0 ){

    // Do nothing--we are already sorted

    return;

}else{

    char* temp = *s1;

    *s1 = *s2;

    *s2 = temp;

}

}

// @Name    bruteForceSort

// @Brief   A simple O(N*N) sorting algorithm.

void bruteForceSort(char** array, unsigned int start, unsigned int end){

    int i,j;

    for(i =start; i < end-1; i++){

        for(j =start; j < end-1; j++){

            // Note the swap here.

            swapStrings(&array[j],&array[j+1]);

        }

   }

}

// @Name    partition

// @Brief   Helper funcion for quicksort

int partition(char** array, unsigned int low, unsigned int high){   

if (low < high) // place pivot in it's correct position if more than 1 element
{
   unsigned int pivot = partition(array, low, high); // returns index of pivot placed in it's correct position

   quicksort(array, low, pivot - 1); // quicksort array left of the pivot
   quicksort(array, pivot + 1, high); // quicksort array right of the pivot

}

}

void quicksort(char** array, unsigned int low, unsigned int high){

  

char* pivot = array[low];        // pick pivot as the lowest index string

   unsigned int j = low;            // stores index till which we have probed

   unsigned int i = j - 1;        // stores index below which all strings are smaller than the pivot string

   while(j <= high){                // probe strings till high index

       if (strcmp(array[j], pivot) < 0){       // if new string is smaller than the pivot then swap with string bigger than pivot

           i++;

           swapStrings(&array[i], &array[j]);
       }

       j++;
   }

   swapStrings(&array[i + 1], &array[low]); // swap the pivot to it's correct position

   return i + 1;

}

int main(){

// Load our unsorted music file

// We load two copies, as we will compare two sorting algorithms.

char** musicDatabase1 = loadMusicFile("./musicdatabase.txt",13610);

char** musicDatabase2 = loadMusicFile("./musicdatabase.txt",13610);

// Print out a portion of the music database.

printf("The first 10 entries of 13609 unsorted are...\n");

printArrayOfCharStrings(musicDatabase1,0,10);

printf("\n");

// ===========================================

// ===== Experiment 1 - Using Brute Force Sort ====

// Create a clock to measure the elapsed time

clock_t start1,end1;

start1 = clock();

// perform bruteForceSort after starting your timer

bruteForceSort(musicDatabase1,0,13609);

end1 = clock();

double experiment1 = ((double)(end1-start1)/CLOCKS_PER_SEC);

   // ===========================================

  

// ===========================================

// ===== Experiment 2 - Using Quick Sort ====

//printArrayOfCharStrings(musicDatabase2,0,994);

// Create a clock to measure the elapsed time

clock_t start2,end2;

start2 = clock();

// perform quicksort after starting your timer

quicksort(musicDatabase2,0,13609);

end2 = clock();

double experiment2 = ((double)(end2-start2)/CLOCKS_PER_SEC);

// ===========================================

// check correctness

const int items = 10; // change this to up to 13609

printf("O(N*N) sort produces\n");

printArrayOfCharStrings(musicDatabase1,0,items);

printf("\n quick sort produces\n");

printArrayOfCharStrings(musicDatabase2,0,items);

// ============ Results ==============

printf("\nResults of sorting:\n");

printf("%f time taking for brute force\n", experiment1);

printf("%f time taking for quick sort\n", experiment2);

return 0;

}

Note :- The music data file was not provided so i am unable to provide the sample output.