import java.util.Arrays;

/**

* This is a skeleton file for your homework. Edit the sections marked TODO. You

* may add new functions. You may also edit the function "main" to test your

* code.

*

* You must not add static variables. You MAY add static functions, just not

* static variables.

*

* It is okay to add functions, such as

*

*

 
 * public static double sumHelper (double[] list, int i, double sumSoFar) {
 
 * 

*

* but it is NOT okay to add static variables, such as

*

*

 
 * public static int x;
 
 * 

*

* As for homework 1, you must not change the declaration of any method.

*

* You can edit the main function all you want. I will not run your main

* function when grading.

*/

public class Recursion {

/**

* As a model, here is a minValue function, both iteratively and recursively

*/

/** iterative version */

public static double minValueIterative (double[] list) {

double result = list[0];

int i = 1;

while (i < list.length) {

if (list[i] < result) result = list[i];

i = i + 1;

}

return result;

}

/** recursive version */

public static double minValue (double[] list) {

return minValueHelper (list, 1, list[0]);

}

private static double minValueHelper (double[] list, int i, double result) {

if (i < list.length) {

if (list[i] < result) result = list[i];

result = minValueHelper (list, i + 1, result);

}

return result;

}

/**

* PROBLEM 1: Translate the following sum function from iterative to

* recursive.

*

* You should write a helper method. You may not use any "fields" to solve

* this problem (a field is a variable that is declared "outside" of the

* function declaration --- either before or after).

*/

public static double sumIterative (double[] a) {

double result = 0.0;

int i = 0;

while (i < a.length) {

result = result + a[i];

i = i + 1;

}

return result;

}

public static double sum (double[] a) {

return 0; // TODO

}

/**

* PROBLEM 2: Do the same translation for this in-place reverse function

*

* You should write a helper method. You may not use any "fields" to solve

* this problem (a field is a variable that is declared "outside" of the

* function declaration --- either before or after).

*/

public static void reverseIterative (double[] a) {

int hi = a.length - 1;

int lo = 0;

while (lo < hi) {

double loVal = a[lo];

double hiVal = a[hi];

a[hi] = loVal;

a[lo] = hiVal;

lo = lo + 1;

hi = hi - 1;

}

}

public static void reverse (double[] a) {

// TODO

}

/**

* @param args

*/

public static void main (String[] args) {

double[] list0 = new double[] {};

double[] list1 = new double[] { 5 };

double[] list2 = new double[] { -3, 5 };

double[] list3 = new double[] { 2, -3, 5 };

double[] list4 = new double[] { -1, 2, -3, 5 };

double[] list5 = new double[] { 33, 44, 55 };

System.out.println("Display the sum of the array contents");

System.out.println ("list5: " +sum (list5));

System.out.println ("list0: " +sum (list0));

System.out.println ("list1: " +sum (list1));

System.out.println ("list2: " +sum (list2));

System.out.println ("list3: " +sum (list3));

System.out.println ("list4: " +sum (list4));

System.out.println("Reversing the lists");

reverse (list0);

System.out.println ("list0: " +Arrays.toString (list0));

reverse (list1);

System.out.println ("list1: " +Arrays.toString (list1));

reverse (list2);

System.out.println ("list2: " +Arrays.toString (list2));

reverse (list3);

System.out.println ("list3: " +Arrays.toString (list3));

reverse (list4);

System.out.println ("list4: " +Arrays.toString (list4));

reverse (list5);

System.out.println ("list5: " +Arrays.toString (list5));

}

}