Rewrite the quick sort function as a descending order sort. Do not simply sort i
ID: 3837159 • Letter: R
Question
Rewrite the quick sort function as a descending order sort. Do not simply sort items in ascending order and then reverse the order of the array elements.
Write a program to test your function.
ARRAYLISTYPE.H
#ifndef H_arrayListType
#define H_arrayListType
#include <iostream>
#include <cassert>
using namespace std;
template <class elemType>
class arrayListType
{
public:
int findKthLargest(vector<int>& v, int kth);
void build(vector<int>& v);
void heapify(vector<int>& v, int low, int high);
const arrayListType<elemType>& operator=
(const arrayListType<elemType>&);
//Overloads the assignment operator
bool isEmpty();
//Function to determine whether the list is empty
//Postcondition: Returns true if the list is empty;
// otherwise, returns false.
bool isFull();
//Function to determine whether the list is full.
//Postcondition: Returns true if the list is full;
// otherwise, returns false.
int listSize();
//Function to determine the number of elements in the list
//Postcondition: Returns the value of length.
int maxListSize();
//Function to determine the size of the list.
//Postcondition: Returns the value of maxSize.
void print() const;
//Function to output the elements of the list
//Postcondition: Elements of the list are output on the
// standard output device.
bool isItemAtEqual(int location, const elemType& item);
//Function to determine whether the item is the same
//as the item in the list at the position specified by
//Postcondition: Returns true if the list[location]
// is the same as the item; otherwise,
// returns false.
void insertAt(int location, const elemType& insertItem);
//Function to insert an item in the list at the
//position specified by location. The item to be inserted
//is passed as a parameter to the function.
//Postcondition: Starting at location, the elements of the
// list are shifted down, list[location] = insertItem;,
// and length++;. If the list is full or location is
// out of range, an appropriate message is displayed.
void insertEnd(const elemType& insertItem);
//Function to insert an item at the end of the list.
//The parameter insertItem specifies the item to be inserted.
//Postcondition: list[length] = insertItem; and length++;
// If the list is full, an appropriate message is
// displayed.
void removeAt(int location);
//Function to remove the item from the list at the
//position specified by location
//Postcondition: The list element at list[location] is removed
// and length is decremented by 1. If location is out of
// range,an appropriate message is displayed.
void retrieveAt(int location, elemType& retItem);
//Function to retrieve the element from the list at the
//position specified by location.
//Postcondition: retItem = list[location]
// If location is out of range, an appropriate message is
// displayed.
void replaceAt(int location, const elemType& repItem);
//Function to replace the elements in the list at the
//position specified by location. The item to be replaced
//is specified by the parameter repItem.
//Postcondition: list[location] = repItem
// If location is out of range, an appropriate message is
// displayed.
void clearList();
//Function to remove all the elements from the list.
//After this operation, the size of the list is zero.
//Postcondition: length = 0;
int seqSearch(const elemType& item);
//Function to search the list for a given item.
//Postcondition: If the item is found, returns the location
// in the array where the item is found; otherwise,
// returns -1.
void insert(const elemType& insertItem);
//Function to insert the item specified by the parameter
//insertItem at the end of the list. However, first the
//list is searched to see whether the item to be inserted
//is already in the list.
//Postcondition: list[length] = insertItem and length++
// If the item is already in the list or the list
// is full, an appropriate message is displayed.
void remove(const elemType& removeItem);
//Function to remove an item from the list. The parameter
//removeItem specifies the item to be removed.
//Postcondition: If removeItem is found in the list,
// it is removed from the list and length is
// decremented by one.
void selectionSort();
//Function to sort array list using selection sort algorithm
void insertionSort();
//Function to sort array list using selection sort algorithm
void intervalInsertionSort(int firstPosition, int increment);
//Function to partially sort array using interval insertion sort algorithm
void shellSort();
//Function to sort array list using shell sort algorithm
void quickSort();
//Function to sort array list using quick sort algorithm
void heapSort();
//Function to sort array list using heap sort algorithm
arrayListType(int size = 100);
//constructor
//Creates an array of the size specified by the
//parameter size. The default array size is 100.
//Postcondition: The list points to the array, length = 0,
// and maxSize = size
arrayListType(const arrayListType<elemType>& otherList);
//copy constructor
~arrayListType();
//destructor
//Deallocates the memory occupied by the array.
protected:
elemType *list; //array to hold the list elements
int length; //to store the length of the list
int maxSize; //to store the maximum size of the list
void swap(int first, int second);
int minLocation(int first, int last);
private:
int partition(int first, int last);
void recQuickSort(int first, int last);
void buildHeap();
void heapify(int low, int high);
};
template <class elemType>
void arrayListType<elemType>::build(vector<int>& v)
{
int temp;
int n = v.size();
for (int i = n / 2 - 1; i >= 0; i--)
heapify(v, n, i);
for (int i = n - 1; i >= 0; i--)
{
// Move current root to end
temp = v[0];
v[0] = v[i];
v[i] = temp;
// call max heapify on the reduced heap
heapify(v, i, 0);
}
}
template <class elemType>
void arrayListType<elemType>::heapify(vector<int>& v, int low, int high)
{
int largest = low; // Initialize largest as root
int l = 2 * low + 1; // left = 2*i + 1
int r = 2 * low + 2; // right = 2*i + 2
int temp;
// If left child is larger than root
if (l < high && v[l] > v[largest])
largest = l;
// If right child is larger than largest so far
if (r < high && v[r] > v[largest])
largest = r;
// If largest is not root
if (largest != low)
{
//swap(arr[i], arr[largest]);
temp = v[low];
v[low] = v[largest];
v[largest] = temp;
// Recursively heapify the affected sub-tree
heapify(v, high, largest);
}
}
template <class elemType>
int arrayListType<elemType>::findKthLargest(vector<int>& v, int kth)
{
//build(v);
cout << " The " << kth << " element is -->" << v[kth - 1] << endl;
return kth;
}
template <class elemType>
bool arrayListType<elemType>::isEmpty()
{
return (length == 0);
}
template <class elemType>
bool arrayListType<elemType>::isFull()
{
return (length == maxSize);
}
template <class elemType>
int arrayListType<elemType>::listSize()
{
return length;
}
template <class elemType>
int arrayListType<elemType>::maxListSize()
{
return maxSize;
}
template <class elemType>
void arrayListType<elemType>::print() const
{
for (int i = 0; i < length; i++)
cout << list[i] << " ";
cout << endl;
}
template <class elemType>
bool arrayListType<elemType>::isItemAtEqual
(int location, const elemType& item)
{
return(list[location] == item);
}
template <class elemType>
void arrayListType<elemType>::insertAt
(int location, const elemType& insertItem)
{
if (location < 0 || location >= maxSize)
cerr << "The position of the item to be inserted "
<< "is out of range" << endl;
else
if (length >= maxSize) //list is full
cerr << "Cannot insert in a full list" << endl;
else
{
for (int i = length; i > location; i--)
list[i] = list[i - 1]; //move the elements down
list[location] = insertItem; //insert the item at the
//specified position
length++; //increment the length
}
} //end insertAt
template <class elemType>
void arrayListType<elemType>::insertEnd(const elemType& insertItem)
{
if (length >= maxSize) //the list is full
cerr << "Cannot insert in a full list" << endl;
else
{
list[length] = insertItem; //insert the item at the end
length++; //increment the length
}
} //end insertEnd
template <class elemType>
void arrayListType<elemType>::removeAt(int location)
{
if (location < 0 || location >= length)
cerr << "The location of the item to be removed "
<< "is out of range" << endl;
else
{
for (int i = location; i < length - 1; i++)
list[i] = list[i + 1];
length--;
}
} //end removeAt
template <class elemType>
void arrayListType<elemType>::retrieveAt
(int location, elemType& retItem)
{
if (location < 0 || location >= length)
cerr << "The location of the item to be retrieved is "
<< "out of range." << endl;
else
retItem = list[location];
} //end retrieveAt
template <class elemType>
void arrayListType<elemType>::replaceAt
(int location, const elemType& repItem)
{
if (location < 0 || location >= length)
cerr << "The location of the item to be replaced is "
<< "out of range." << endl;
else
list[location] = repItem;
} //end replaceAt
template <class elemType>
void arrayListType<elemType>::clearList()
{
length = 0;
} //end clearList
template <class elemType>
int arrayListType<elemType>::seqSearch(const elemType& item)
{
int loc;
bool found = false;
for (loc = 0; loc < length; loc++)
if (list[loc] == item)
{
found = true;
break;
}
if (found)
return loc;
else
return -1;
} //end seqSearch
template <class elemType>
void arrayListType<elemType>::insert(const elemType& insertItem)
{
int loc;
if (length == 0) //list is empty
list[length++] = insertItem; //insert the item and
//increment the length
else if (length == maxSize)
cerr << "Cannot insert in a full list." << endl;
else
{
loc = seqSearch(insertItem);
if (loc == -1) //the item to be inserted
//does not exist in the list
list[length++] = insertItem;
else
cerr << "the item to be inserted is already in "
<< "the list. No duplicates are allowed." << endl;
}
} //end insert
template<class elemType>
void arrayListType<elemType>::remove(const elemType& removeItem)
{
int loc;
if (length == 0)
cerr << "Cannot delete from an empty list." << endl;
else
{
loc = seqSearch(removeItem);
if (loc != -1)
removeAt(loc);
else
cout << "The item to be deleted is not in the list."
<< endl;
}
} //end remove
template <class elemType>
arrayListType<elemType>::arrayListType(int size)
{
if (size < 0)
{
cerr << "The array size must be positive. Creating "
<< "an array of size 100. " << endl;
maxSize = 100;
}
else
maxSize = size;
length = 0;
list = new elemType[maxSize];
assert(list != NULL);
}
template <class elemType>
arrayListType<elemType>::~arrayListType()
{
delete[] list;
}
template <class elemType>
arrayListType<elemType>::arrayListType
(const arrayListType<elemType>& otherList)
{
maxSize = otherList.maxSize;
length = otherList.length;
list = new elemType[maxSize]; //create the array
assert(list != NULL); //terminate if unable to allocate
//memory space
for (int j = 0; j < length; j++) //copy otherList
list[j] = otherList.list[j];
} //end copy constructor
template <class elemType>
const arrayListType<elemType>& arrayListType<elemType>::operator=
(const arrayListType<elemType>& otherList)
{
if (this != &otherList) //avoid self-assignment
{
delete[] list;
maxSize = otherList.maxSize;
length = otherList.length;
list = new elemType[maxSize]; //create the array
assert(list != NULL); //if unable to allocate memory
//space, terminate the program
for (int i = 0; i < length; i++)
list[i] = otherList.list[i];
}
return *this;
}
template <class elemType>
void arrayListType<elemType>::selectionSort()
{
int minIndex;
for (int loc = 0; loc < length - 1; loc++)
{
minIndex = minLocation(loc, length - 1);
swap(loc, minIndex);
}
} //end selectionSort
template<class elemType>
void arrayListType<elemType>::insertionSort()
{
int firstOutOfOrder, location;
elemType temp;
for (firstOutOfOrder = 1; firstOutOfOrder < length; firstOutOfOrder++)
if (list[firstOutOfOrder] < list[firstOutOfOrder - 1])
{
temp = list[firstOutOfOrder];
location = firstOutOfOrder;
do
{
list[location] = list[location - 1];
location--;
} while (location > 0 && list[location - 1] > temp);
list[location] = temp;
}
} //end insertionSort
template <class elemType>
void arrayListType<elemType>::intervalInsertionSort(int start, int increment)
{
int firstOutOfOrder, location;
elemType temp;
for (firstOutOfOrder = start + increment; firstOutOfOrder < length; firstOutOfOrder += increment)
if (list[firstOutOfOrder] < list[firstOutOfOrder - increment])
{
temp = list[firstOutOfOrder];
location = firstOutOfOrder;
do
{
list[location] = list[location - increment];
location -= increment;
} while (location > start && list[location - increment] > temp);
list[location] = temp;
}
} //end insertvalInsertionSort
template <class elemType>
void arrayListType<elemType>::shellSort()
{
int inc;
for (inc = 1; inc < (length - 1) / 9; inc = 3 * inc + 1)
;
do
{
for (int begin = 0; begin < inc; begin++)
{
intervalInsertionSort(begin, inc);
print();
}
inc = inc / 3;
} while (inc > 0);
} //end shellSort
template <class elemType>
void arrayListType<elemType>::quickSort()
{
recQuickSort(0, length - 1);
}
template <class elemType>
void arrayListType<elemType>::recQuickSort(int first, int last)
{
int pivotLocation;
if (first < last)
{
pivotLocation = partition(first, last);
recQuickSort(first, pivotLocation - 1);
recQuickSort(pivotLocation + 1, last);
}
}
template <class elemType>
int arrayListType<elemType>::partition(int first, int last)
{
elemType pivot;
int index, smallIndex;
swap(first, (last + first) / 2);
pivot = list[first];
smallIndex = first;
for (index = first + 1; index <= last; index++)
if (list[index] < pivot)
{
smallIndex++;
swap(smallIndex, index);
}
swap(first, smallIndex);
return smallIndex;
}
template <class elemType>
void arrayListType<elemType>::heapSort()
{
elemType temp;
buildHeap();
for (int lastOutOfOrder = length - 1; lastOutOfOrder >= 0; lastOutOfOrder--)
{
temp = list[lastOutOfOrder];
list[lastOutOfOrder] = list[0];
list[0] = temp;
heapify(0, lastOutOfOrder - 1);
}
}
template <class elemType>
void arrayListType<elemType>::buildHeap()
{
for (int index = length / 2 - 1; index >= 0; index--)
heapify(index, length - 1);
}
template <class elemType>
void arrayListType<elemType>::heapify(int low, int high)
{
int largeIndex = 2 * low + 1; //index of left child
elemType temp = list[low]; //make copy of root node of subtree
while (largeIndex <= high)
{
if (largeIndex < high)
if (list[largeIndex] < list[largeIndex + 1])
largeIndex = largeIndex + 1;
if (temp > list[largeIndex]) //subtree is already in a heap
break;
else
{
list[low] = list[largeIndex]; //move the larger child to the root
low = largeIndex; //go to the subtree to restore the heap
largeIndex = 2 * low + 1;
}
}
list[low] = temp; //insert temp into the tree, that is the list
} //end heapify
template <class elemType>
int arrayListType<elemType>::minLocation(int first, int last)
{
int minIndex;
minIndex = first;
for (int loc = first + 1; loc <= last; loc++)
if (list[loc] < list[minIndex])
minIndex = loc;
return minIndex;
} //end minLocation
template <class elemType>
void arrayListType<elemType>::swap(int first, int second)
{
elemType temp;
temp = list[first];
list[first] = list[second];
list[second] = temp;
}//end swap
#endif
SOURCE.CPP
#include <iostream>
#include <ctime>
#include <random>
#include <string>
#include "arrayListType.h"
#include<vector>
using namespace std;
int main()
{
vector<int> data;
const unsigned upper_bound = 99;
const unsigned lower_bound = 10;
const int length = 8;
default_random_engine e;
unsigned seed = static_cast<unsigned>(time(NULL));
e.seed(seed);
uniform_int_distribution<unsigned> u(lower_bound, upper_bound);
arrayListType<int> al(16);
while (al.listSize() < al.maxListSize())
{
al.insert(u(e));
al.print();
data.push_back(u(e));
}
cout << "---" << endl;
al.heapSort();
//al.selectionSort();
//al.print();
//al.quickSort();
al.print();
cout << "The vector elements are :-->" << endl;
for (int i = 0;i<data.size();i++)
{
cout << data[i] << " ";
}
al.build(data);
cout << endl << "The vector elements after heapsort:-->" << endl;
for (int i = 0;i<data.size();i++)
{
cout << data[i] << " ";
}
al.findKthLargest(data, 2);
cout << endl;
system("pause");
return 0;
}
Explanation / Answer
Hi,
We can write program in C++ for quick sort to do descending order . please find the below code for your reference.
include<iostream.h>
#include<conio.h>
int a[10],l,u,i,j;
void quick(int *,int,int);
void main()
{
clrscr();
cout <<"enter 10 elements";
for(i=0;i<10;i++)
cin >> a[i];
l=0;
u=9;
quick(a,l,u);
cout <<"descending sorted elements";
for(i=0;i<10;i++)
cout << a[i] << " ";
getch();
}
void quick(int a[],int l,int u)
{
int p,temp;
if(l<u)
{
p=a[l];
i=l;
j=u;
while(i<j)
{
while(a[i] > p && i<j )
i++;
while(a[j]<=p && i<=j )
j--;
if(i<=j)
{
temp=a[i];
a[i]=a[j];
a[j]=temp;
}
}
temp=a[j];
a[j]=a[l];
a[l]=temp;
cout <<" ";
for(i=0;i<10;i++)
cout <<a[i]<<" ";
quick(a,l,j-1);
quick(a,j+1,u);
}
}
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