Question

public static int[] collatz(int start,
                            int numIterations)

Given integer start and integer numIterations, return an array containing the Collatz sequence beginning with start up to numIterations. The Collatz function is defined by: 3n + 1 if n is odd n/2 if n is even Given start = 7 and numIterations = 3, this method returns [7, 22, 11, 34]

Parameters:

start - starting integer

numIterations - how long to compute the Collatz sequence for

Returns:

an array containing the Collatz sequence beginning with start up to numIterations.

Answer 1

import java.util.Arrays;

public class CollatzSequence {

    public static int[] collatz(int start, int numIterations) {
        int[] result = new int[numIterations+1];
        result[0] = start;
        for (int i = 1; i <= numIterations; i++) {
            if (result[i-1] % 2 == 0) {
                result[i] = result[i-1] / 2;
            } else {
                result[i] = 3*result[i-1] + 1;
            }
        }
        return result;
    }

    public static void main(String[] args) {
        System.out.println(Arrays.toString(collatz(7, 3)));
    }
}