Question

Implement the following sorting algorithms using Java:
a. Heap Sort. b. Quick Sort. c. Radix Sort.
Verify the correctness of each implemented algorithm by sorting the following array:
10, 5, 60, 53, 45, 3, 25,37,39,48

the code should be in one class and I would like to use the switch statement

Answer 1

Answer:

a)HEAP SORT:

It is a comparison based sorting technique
It is based on Binary Heap data structure.
Heap Sort Algorithm :
1. Build max heap from input data.
2. Now,the largest item is present at root of the heap. Replace it with the last node of heap then reduce size of heap by Then,heapify the root of tree.
3. Repeat above steps while size of heap is greater than 1.

CODE:

import java.util.Scanner;
public class Main{
static void heapify(int a[],int n,int i){
int largest=i; // Initialize largest as root
int l=2*i+1; // left = 2*i + 1
int r=2*i+2; // right = 2*i + 2
if(l<n && a[l]>a[largest]) // If left child is larger than root
largest=l;
if(r<n && a[r]>a[largest]) // If right child is larger than largest so far
largest=r;
if(largest!=i){ // If largest is not root
int swap=a[i];
a[i]=a[largest];
a[largest]=swap;
heapify(a,n,largest); // Recursively heapify the affected sub-tree
}
}
static void sort(int a[]){
int n=a.length;
int i;
for(i=n/2-1;i>= 0;i--) // Build heap
heapify(a,n,i);
for(i=n-1;i>=0;i--){ // One by one extract an element from heap then Move current root to end
int temp=a[0];
a[0]=a[i];
a[i]=temp;
heapify(a,i,0); // call max heapify on the reduced heap
}
}
static void print_array(int a[]){
int n=a.length;
for (int i=0;i<n;++i)
System.out.print(a[i]+" ");
System.out.println();
}
public static void main(String args[]){
int n;
Scanner sc=new Scanner(System.in);
System.out.print("Enter no. of elements you want in array:");
n=sc.nextInt();
int a[] = new int[n];
System.out.println("Enter all the elements:");
for(int i=0;i<n;i++){
a[i]=sc.nextInt();
}
sort(a);
System.out.print("sorted array : ");
print_array(a);
}
}

Screenshots of the code shown below:

OUTPUT:

b)QUICK SORT:

It is a Divide and Conquer algorithm.
It choose an element as pivot & partitions given array around the pivot.
The key process in quickSort is partition().

CODE:

import java.util.Scanner;
class Main{
static int partition(int a[],int low,int high){
int j;
int pivot=a[high];
int i=low-1;
for(j=low;j<high;j++){
if(a[j]<pivot){
i++;
int temp=a[i];
a[i]=a[j];
a[j]=temp;
}
}
int temp=a[i+1];
a[i+1]=a[high];
a[high]=temp;
return i+1;
}
static void sort(int a[],int low,int high){
if(low<high){
int pi=partition(a,low,high);
sort(a,low,pi-1);
sort(a,pi+1,high);
}
}
static void print_array(int a[]){
int i;
int n=a.length;
for(i=0;i<n;++i)
System.out.print(a[i]+" ");
System.out.println();
}
public static void main(String args[]){
int n;
Scanner sc=new Scanner(System.in);
System.out.print("Enter no. of elements you want in array:");
n=sc.nextInt();
int a[] = new int[n];
System.out.println("Enter all the elements:");
for(int i=0;i<n;i++){
a[i]=sc.nextInt();
}
sort(a, 0, n-1);
System.out.print("sorted array : ");
print_array(a);
}
}

Screenshots of the code shown below:

OUTPUT:

c)RADIX SORT:

Radix Sort sort an array in linear time.
It uses counting sort as subroutine to sort.

CODE:

import java.io.*;
import java.util.*;
class Main{
static int getMax(int a[],int n){ //function to get maximum value in array
int max=a[0];
int i;
for(i=1;i<n;i++)
if(a[i]>max)
max=a[i];
return max;
}
static void countSort(int a[],int n,int exp){ //function to do counting sort of array
int output[]=new int[n]; // output array
int i;
int count[]=new int[10];
Arrays.fill(count,0);
for(i=0;i<n;i++) // Store count of occurrences in count[]
count[(a[i]/exp)%10]++;
//Change count[i] so that count[i] contains actual position of digit in output[]
for(i=1;i<10;i++)
count[i]+=count[i-1];
for (i = n - 1; i >= 0; i--){ // Build the output array
output[count[ (a[i]/exp)%10 ] - 1] = a[i];
count[ (a[i]/exp)%10 ]--;
}
for(i=0;i<n;i++) //Copy the output array to arr[]
a[i]=output[i];
}
static void sort(int a[],int n){
int m=getMax(a,n); //Find maximum to know number of digits
for (int exp = 1; m/exp > 0; exp *= 10) // Do counting sort for every digit
countSort(a,n,exp);
}
static void print_array(int a[]){
int n = a.length;
for(int i=0; i<n; i++)
System.out.print(a[i]+" ");
}
public static void main(String args[]){
int n;
Scanner sc=new Scanner(System.in);
System.out.print("Enter no. of elements you want in array:");
n=sc.nextInt();
int a[] = new int[n];
System.out.println("Enter all the elements:");
for(int i=0;i<n;i++){
a[i]=sc.nextInt();
}
sort(a,n);
System.out.print("sorted array : ");
print_array(a);
}
}

Screenshots of the code shown below:

OUTPUT:

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