Nsryjdtyk

Problem

We have a robot that can pickup blocks from a stash, move them
horizontally and lower them in place. There are 10 positions available
to lower blocks number 0 to 9. Each position can hold up to 15 blocks.

The robot understands the commands 'P', 'M' and 'L':

• P: Pickup from the stash and move to position 0


• M: Move to the Next Position


• L: Lower the block

The robot is safe to operate and very forgiving:

• There are always blocks in the stash (Pickup always gets a block)


• If the robot already holds a block, Pickup will reset position to 0


• The robot will not go beyond position 9, Trying to move further does nothing


• Lowering the block on a pile of 15 does nothing


• Lowering without a block does nothing


• Robot ignores any command that is not 'P', 'M','L'

Implement a function that takes a String of commands for the robot.
The function should output String representing the number of blocks
(in hexadecimal) at each position after running all the commands

Solution

I have implemented it and it works fine and all but I feel like this is not the correct way.

Key errors I feel are how I determine Hexadecimal values from A to F. What is the correct way of doing this other than using a hashmap?

Also, processing of each command using switch-case feels so verbose as well.

Has anyone solved this problem before? What's the optimal way of doing this?

private static int stash = new int[10];

private static HashMap<Integer, String> map = new HashMap<Integer, String>();

public static void main(String args) {

    map.put(10, "A");

    map.put(11, "B");

    map.put(12, "C");

    map.put(13, "D");

    map.put(14, "E");

    map.put(15, "F");



    String command = "PMLPMLPMLPMLPMLPMLPMLPMLPMLPMLPMLPMLPMLPMLPMLPMLPMLPMLPMMMLPMLPMMLPMMMMMMMMMMLPMMMMMMMMMML";

    executeCommand(command);

}



private static void executeCommand(String command) {

    int block = 0;

    int stashLocation = 0;

    for (Character c : command.toCharArray()) {

        switch (c) {

            case 'P':

                if (block == 0) {

                    block = 1;

                } else {

                    stashLocation = 0;

                }

                break;

            case 'M':

                if (stashLocation < 9) {

                    stashLocation++;

                }

                break;

            case 'L':

                if (block != 0 && stash[stashLocation] < 15) {

                    stash[stashLocation] = stash[stashLocation] + 1;

                    block = 0;

                    stashLocation = 0;

                }

                break;

        }

    }

    Arrays.stream(stash).forEach(val -> {

        if (map.containsKey(val)) {

            System.out.print(map.get(val));

        } else {

            System.out.print(val);

        }

    });

}