// Allison Obourn, CSE 142
// Examples of using arrays as parameters and returns

import java.util.*;

public class ArrayExamples {
	public static void main(String[] args) {
		int[] numbers = {11, 42, -5, 7, 27, 0, 89};
		int[] numbers2 = {1, 43, 65, 0, 2, 54, 8};
		
		System.out.println(Arrays.toString(numbers));
		System.out.println(Arrays.toString(numbers2));
		//reverse(numbers);
		// swap(numbers, 1, 3);
		//swapAll(numbers, numbers2);
		int[] merged = merge(numbers, numbers2);
		System.out.println(Arrays.toString(merged));
		//System.out.println(Arrays.toString(numbers2));
	}
	
	// Merges the three passed in arrays returning an array the size of 
	// all three combined with a1's contents first followed by a2's and 
	// finally a3's. 
	public static int[] merge3(int[] a1, int[] a2, int[] a3) {
		// functional but long implementation
		/*	
		int[] a4 = new int[a1.length + a2.length + a3.length];
		
		for(int i = 0; i < a1.length; i++) {
			a4[i] = a1[i];
		}
		
		// a1 = [1, 2, 4]
		for(int i = 0; i < a2.length; i++) {
			a4[i + a1.length] = a2[i];
		}
		
		for(int i = 0; i < a3.length; i++) {
			a4[i + a1.length + a2.length] = a3[i];
		}
		
		return a4;
		*/
		
		return merge(merge(a1, a2),a3);
	}
	
	// Takes two arrays and returns an array the size of both combined
	// with the contents of a1 at the beginning followed by a2's contents
	public static int[] merge(int[] a1, int[] a2) {
		int[] a3 = new int[a1.length + a2.length];
		
		for(int i = 0; i < a1.length; i++) {
			a3[i] = a1[i];
		}
		
		for(int i = 0; i < a2.length; i++) {
			a3[i + a1.length] = a2[i];
		}
		
		return a3;
	}
	
	// takes two arrays of the same length and swaps their contents 
	public static void swapAll(int[] a1, int[] a2) {
		for(int i = 0 ; i < a1.length; i++) {
			int temp = a1[i];
			a1[i] = a2[i];
			a2[i] = temp;
		}
	}
	
	// takes an array and two indecies. Swaps the elements in the 
	// array stored at the two indecies.
	public static void swap(int[] a, int first, int last) {
		int temp = a[first];
		a[first] = a[last];
		a[last] = temp;
	}

	// takes an array and reverses it. 
	public static void reverse(int[] numbers) {
		for(int i = 0; i < numbers.length / 2; i++) {
			int temp = numbers[i];
			numbers[i] = numbers[numbers.length - 1 - i];
			numbers[numbers.length - 1 - i] = temp;
		}
	}
}