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