Two Numbers

	/**
	 * Find two numbers in an array whose sum is x
	 * 
	 * Let A be an array of random integers and a given integer x. Find all
	 * pairs of numbers from the array whose sum is equal to x.
	 * 
	 * 
	 * The problem has different versions according to different
conditions,
	 * including:
	 * 
	 * - Unsorted array with O(1) space 
	 * - Sorted array with O(1) space 
	 * - Using extra space
	 * 
	 * */

	/**
	 * 1. The Brute Method.
	 * */

	/**
	 * 2. O(n) Method for Sorted Array.
	 * */
	
	/**
	 * 3. O(n) Method using Hash Table. 
	 * */