/*
 * File: even_odd.kt
 * Purpose: This program demonstrates mutual recursion in a simple
 *   setting
 */

fun main() {
     for (i in -5..5) {
         println(if (even(i)) "$i is even" else "$i is odd");
     }

     println();

     for (i in -5..5) {
         println(if (odd(i)) "$i is odd" else "$i is even");
     }
}

fun even(n: Int): Boolean {
    return when {
        n < 0 -> even(-n)
        n == 0 -> true
        else -> odd(n-1)
    }
}

fun odd(n: Int): Boolean {
    return when {
        n < 0 -> odd(-n)
        n == 0 -> false
        else -> even(n-1)
    }
}