⬅ Quicksort | A Helpful Line-by-Line Code Tutorial | Part 1

public class QuickSortTest {

	public static final int max = 10;
	
	public static void main(String[] args){
		
		int[] toSortArray = new int[max];
	
		for(int i = 0; i < max; i++){
			
			toSortArray[i] = (int) (Math.random()*100);
			
		}
		
		System.out.println("The array to be sorted is:");
		
		for(int i = 0; i < max; i++){
			
			System.out.print(" | " + toSortArray[i]);
		}
		System.out.println(" | ");
		
		//Beginning of the algorithm

			quicksortHelper(toSortArray, 0 , max-1);
		
		// End of the algorithm
		
		System.out.println("The sorted array is: ");
		
		for(int i = 0; i < max; i++){
			
			System.out.print(" | " + toSortArray[i]);
		}
		System.out.println(" | ");
		
	}

	private static void quicksortHelper(int[] toSortArray, int first, int last) {
		
		if(first < last){
			
			int splitpoint = partition(toSortArray, first, last);
			quicksortHelper(toSortArray, first, splitpoint-1);
			quicksortHelper(toSortArray, splitpoint+1, last);
			
		}
		
	}

	private static int partition(int[] toSortArray, int first, int last) {
		
		int pivot = toSortArray[first];
		int leftmark = first+1;
		int rightmark = last;
		boolean done = true;
		
		while(done){
			
			while(leftmark<=rightmark && toSortArray[leftmark] < pivot){
				
				leftmark++;
				
			}
			
			while(leftmark<=rightmark && toSortArray[rightmark] > pivot){
				
				rightmark--;
				
			}
			
			if(leftmark>rightmark){
				
				done = false;
				
			}else{
				
				int temp = toSortArray[leftmark];
				toSortArray[leftmark] = toSortArray[rightmark];
				toSortArray[rightmark] = temp;
				
			}
			
		}
		
		int temp = toSortArray[rightmark];
		toSortArray[rightmark] = toSortArray[first];
		toSortArray[first] = temp;
		
		return rightmark;
	}

	
	
		
}