gistfile1.txt

import java.util.*;

public class QuickSort <T extends Comparable<T>>{

    public void swap(ArrayList<T> array, T value1, T value2){
        T temp;
        temp = value1;
        array.set(array.indexOf(value1), value2);
        array.set(array.indexOf(value2), temp);
    }

    public void quickSort(ArrayList<T> arrayList){
        int low = 0;
        int high = arrayList.size()-1;
        quick(arrayList, low, high);
    }

    public void quick(ArrayList<T> arrayList, int low, int high){
        if (low < high){
            int p = partition(arrayList, low, high);
            quick(arrayList, low, p-1);
            quick(arrayList, p+1, high);
        }
    }

    public int partition(ArrayList<T> arrayList, int lower, int high){
       T pivot = arrayList.get(high);
       int partition = lower;
       for (int j = lower; j < high; j++){
           if (arrayList.get(j).compareTo(pivot) <= 0){
               swap(arrayList, arrayList.get(partition), arrayList.get(j));
               partition = partition + 1;
           }
       }
       swap(arrayList, arrayList.get(partition), arrayList.get(partition));
       return partition;
    }

    public static void main(String[] args) {
        QuickSort<Integer> quickSort = new QuickSort<>();
        Scanner scanner = new Scanner(System.in);
        System.out.println("what is your number?");
        int size = scanner.nextInt();
        ArrayList<Integer> arrayList = new ArrayList<>();

       /* for (int i = 0; i < size; i++){
            arrayList.add(i, (int)(Math.random()*200));
        }*/
       arrayList.add(45);
       arrayList.add(20);
       arrayList.add(50);
       System.out.println(Arrays.toString(arrayList.toArray()));

        //quickSort.swap(arrayList, 0, 2);
       quickSort.quickSort(arrayList);
        /*Collections.sort(arrayList, new Comparator<Integer>() {
            @Override
            public int compare(Integer o1, Integer o2) {
                if (o1 == o2){
                    return 0;
                }
                return o1 > o2 ? 1: -1;
            }
        });*/

        System.out.println(arrayList.toString());
    }

}