Question

thank u so much for helping!

2. Exercise 13.3: page 761 Problems #8 (15 points) The preferred alternative to the approach in Exercise #7 suggested in the text was to ignore all sublists with fewer than LOWER_BOUND elements, not splitting them further. When execution of the quicksort algorithm terminates, simply sort the list using insertion sort. Modify quicksort() to incorporate this modification. Note: Exercise #7: Modify quicksort () to use insertion sort if the sublist has fewer than LOWER_BOUND elements for some constant LOWER_BOUND and use quicksort otherwise.

there is no existing codes, so that's why I don't know how to do this question.

C++ pls
thank you

Answer 1

modified_quicksort.cpp

#include<iostream>
#include<time.h>
#define LOWER_BOUND 3
using namespace std;

// Displaying array
void display(int arr[])
{
   for(int i=0;i<10;i++)
   {
       cout<<arr[i]<<" ";
   }
   cout<<endl;
}

// Insertionsort implementation
void insertionsort(int arr[], int n)
{
   for(int i=1;i<n;i++)
   {
       int j=i-1;
       int key = arr[i];
       while(j>=0 && arr[j]>key)
       {
           arr[j+1]=arr[j];
           j--;
       }
       arr[j+1]=key;
   }
}

// Partition implementation
int partition(int arr[], int low, int high)
{
   if(low<high)
   {
       int i = low-1;
       int pivot = arr[high];
       for(int j=low;j<high;j++)
       {
           if(arr[j]<pivot)
           {
               swap(arr[++i],arr[j]);
           }
       }
       swap(arr[++i],arr[high]);
       return i;
   }
   return -1;
}

void quicksort(int arr[], int low, int high)
{
   // If low<high and partition has atleast LOWER_BOUND number of elements
   if(low<high && high-low+1>=LOWER_BOUND)
   {
       int r = partition(arr,low,high);
       quicksort(arr,low,r-1);
       quicksort(arr,r+1,high);
   }
}

int main()
{
   int arr[10];
   srand(time(NULL));
   // Generating 10 random integers
   for(int i=0;i<10;i++)
   {
       arr[i]=rand()%100;
   }
   // Functiona calling
   cout<<"Array before sorting"<<endl;
   display(arr);
   quicksort(arr,0,9);
   insertionsort(arr,9);
   cout<<"Array after sorting"<<endl;
   display(arr);
   return 0;
}

output sccreenshot:

C:\Users\srini\Desktop>g++ modified_quicksort.cpp C:\Users\srini\Desktop>a.exe Array before sorting 16 36 18 48 81 37 54 33 5 83 Array after sorting 5 16 18 33 36 37 48 54 81 83 C:\Users\srini\Desktop>a.exe Array before sorting 26 14 74 2 57 17 91 19 72 7 Array after sorting 2 7 14 17 19 26 57 72 74 91 C:\Users\srini\Desktop>a.exe Array before sorting 29 62 38 66 71 44 4 92 15 59 Array after sorting 4 15 29 38 44 59 62 66 71 92 C:\Users\srini\Desktop>a.exe Array before sorting 97 3 70 7 2 1 29 55 79 21 Array after sorting 1 2 3 7 21 29 55 70 79 97 C:\Users\srini\Desktop>