Question

The elements of an integer-valued array can be initialized so that a[i] == i in a recursive fashion as follows: An array of size 0 is already initialized; Otherwise set the last element of the array to n-1 (where n is the number of elements in the array, for example, an array of size 3 will have its last element -- index 2-- set to 2; and initialize the portion of the array consisting of the first n-1 elements (i.e., the other elements of the array) Write a void method named init that accepts an integer array, and the number of elements in the array and recursively initializes the array so that a[i] == i.

Answer 1

Answer:

public static void init(int[] arr, int n) {

    if (n==0)

        arr[0] = 0;

    else {

        arr[n-1] = n - 1;

        init(arr, n-1);

    }

}

Explanation:

Create a method called init that takes two parameters, an array and the number of elements in the array

When n reaches 0, set the first element to 0 (This is a base for our recursive method)

Otherwise, set the element in index i to i

Call the init inside the init, this is the recursion part, with same array but decrease the number of elements by 1 (We decrease the number of element by 1 in each time so that it goes through all the elements in the array)