// CSE 143, Winter 2011, Marty Stepp                                       
// This is the code we wrote in the first lecture.                                               
// This program implements and tests a 'stutter' method for arrays.                               
                                                
import java.util.*;                                        
                                               
public class FirstLecture {                                     
    public static void main(String[] args) {                                              
        int[] numbers = { 1000, -3, 29, 42, 12 };                                         
        numbers[0] = 42;                                                        
        System.out.println(Arrays.toString(numbers));                               
        int[] result = stutter(numbers);                                                   
        System.out.println(Arrays.toString(result));                                                     
    }                                              
                                                   
    // Accepts an array of integers as a parameter and returns a new
    // array containing 2 copies of each element from the original.
    // For example, if the method is passed {4, 2, -1, 7}, 
    // it returns {4, 4, 2, 2, -1, -1, 7, 7}.
    // Assumes that a is not null.
    public static int[] stutter(int[] a) {
        int[] b = new int[a.length * 2];
        for (int i = 0; i < a.length; i++) {
            b[2 * i] = a[i];
            b[2 * i + 1] = a[i];
        }
        return b;
    }
    
    // Second solution to stutter problem ("b-based")
    public static int[] stutter2(int[] a) {
        int[] b = new int[a.length * 2];
        for (int i = 0; i < b.length; i++) {
            b[i] = a[i / 2];
        }
        return b;
    }
}