// CSE 373, Winter 2013
// This program compares the runtime of various operations on sets.

import java.util.*; // for Random

public class Lecture15RuntimeTest {
	private static final Random RAND = new Random(42); // random number generator

	public static void main(String[] args) {
		int LENGTH = 1000; // initial length of array to sort
		int RUNS = 13; // how many times to grow by 2?

		for (int i = 0; i < RUNS; i++) {
			int[] a = createSequentialArray(LENGTH);
			Set<Integer> set = new HashSet<Integer>();

			// perform a sort and time how long it takes
			long startTime1 = System.currentTimeMillis();
			for (int n : a) {
				set.add(n);
			}
			long endTime1 = System.currentTimeMillis();

			System.out.printf("%10d elements  =>  %6d ms \n", LENGTH, endTime1 - startTime1);
			LENGTH *= 2; // double size of array for next time
		}
	}

	// Creates an array of the given length, fills it with random
	// non-negative integers, and returns it.
	public static int[] createRandomArray(int length) {
		int[] a = new int[length];
		for (int i = 0; i < a.length; i++) {
			a[i] = RAND.nextInt(1000000000);
		}
		return a;
	}

	// Creates an array of the given length, fills it with ordered
	// non-negative integers, and returns it.
	public static int[] createSequentialArray(int length) {
		int[] a = new int[length];
		for (int i = 0; i < a.length; i++) {
			a[i] = i;
		}
		return a;
	}

	// Creates an array of the given length, fills it with reverse-ordered
	// non-negative integers, and returns it.
	public static int[] createReverseArray(int length) {
		int[] a = new int[length];
		for (int i = 0; i < a.length; i++) {
			a[i] = a.length - 1 - i;
		}
		return a;
	}
}