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102 lines (88 loc) · 1.99 KB
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import java.util.Scanner;
/**
* Implementation of QuickSort
*
* @author Unknown
*
*/
public class Quicksort{
/**
* The main method
*
* @param args Command line arguments
*/
public static void main(String[] args){
Scanner input = new Scanner(System.in);
int[] array;
int size = 0;
//Prompt user to create array and its elements
System.out.print("Enter the size of the array: ");
size = input.nextInt();
array = new int[size];
for (int i = 0; i < size; i++){
System.out.print("For index " + i + ", give an integer input: ");
array[i] = input.nextInt();
}
//Output inputted array
System.out.println("The array is: ");
printarray(array);
System.out.println();
//Run quicksort, and output sorted array
quicksort(array, 0, array.length - 1);
System.out.println("The sorted array is: ");
printarray(array);
System.out.println();
input.close();
}
/**
* QuickSort method
*
* @param ar Array to perform QuickSort
* @param start Start of the array
* @param end End of the array
*/
public static void quicksort(int[] ar, int start, int end){
int[] array;
int i = start, j = end;
if (end-start >= 1){
int pivot = ar[end];
while (i< j){
while (ar[i]<pivot && i<end){
i++;
}
while (ar[j]>=pivot && j>start){
j--;
}
if (i<j){
swap(ar, i, j);
}
} swap(ar, end, i);
quicksort(ar, start, i-1);
quicksort(ar, i+1, end);
} else{
return;
}
}
/**
* Helper Method 1 - Swaps elements of an array
*
* @param ar Array to be used
* @param index1 Index 1 to be switched with Index 2
* @param index2 Index 2 to be switched with Index 1
*/
public static void swap(int[] ar, int index1, int index2){
int temp = ar[index1];
ar[index1] = ar[index2];
ar[index2] = temp;
}
/**
* Helper Method 2 - Prints the elements of an array
*
* @param array Array to be printed
*/
public static void printarray(int[] array){
for (int data : array){
System.out.print(data + " ");
}
}
}