---
id: seminar-04
title: 4th seminar
description: |
  Robot in a maze.
---

:::caution

Deadline for the submission of the bonus is **March 23th 24:00**.

:::

:::tip

In case you have any questions, feel free to reach out either by email, Discord
or just by submitting an issue [here](https://gitlab.fi.muni.cz/xfocko/kb/-/issues/new).

:::

For this bonus you can get 3 K₡ and another 0.5 K₡ for the bonus part of it.

[Source](pathname:///files/pb071/bonuses/04/)

## Introduction

In this task you are given a 2D map for a robot. The map contains multiple markers:

- `^v<>` - which denote the directions the robot will be facing when he steps into
  the cell or starts on it.
- `K` - denotes the key.
- `T` - denotes the treasure.

In case robot lands at the beginning on unknown field, e.g. `.` in the tests, he
faces the direction that is given through the parameter.

Your task is to write the `walk` function that returns end result of the walk.
Walk can end in multiple ways:

- `FOUND_TREASURE` - when you find the treasure
- `FOUND_KEY` - when you find the key
- `OUT_OF_BOUNDS` - when the robot falls off the map
- `INFINITE_LOOP` - in case you will implement the bonus
- `NONE` - which is used right now as a default return in the skeleton, has no meaning
  later on

## Hard requirement

There is only one hard requirement that tests cannot check.

**You are not allowed to use any indexing related to map or your current position**
**in your implementation.**

Reason for this requirement is for you to get used to working with pointers. And
for the implementation of this task it is much easier to use just the pointers.

## Example of run

For a better understanding of your task, I will describe a simple walk with corresponding
function call.

```c
const char *map = (
    ">.v"
    ".K<"
    "..."
);

walk(map, &map[6], '^', 3, 3);
```

For this call, you should return `FOUND_KEY`. Let us walk through the walk ;)

1. Robot is placed at the bottom left corner, there is no direction specified, so
   he follows the direction given by parameter (upwards, denoted as `N`(orth),
   so that we can differentiate markers on the map with the robot when using printing
   function).

   ```
   >.v
   .K<
   N..
   ```

2. Moves up:

   ```
   >.v
   NK<
   ...
   ```

3. Moves up (now covers `>`), changes direction to right:

   ```
   E.v
   .K<
   ...
   ```

4. Moves to right:

   ```
   >Ev
   .K<
   ...
   ```

5. Moves to right, faces south:

   ```
   >.S
   .K<
   ...
   ```

6. Moves down, faces west:

   ```
   >.v
   .KW
   ...
   ```

7. Moves left, founds key, returns `FOUND_KEY`:

   ```
   >.v
   .W<
   ...
   ```

## Bonus part

For the bonus part you are supposed to return `INFINITE_LOOP` in case the robot
is stuck in the infinite loop. There are three tests for it. If you pass only the
easy and medium one, you can get 0.25 K₡ for doing your best and trying it out. :)

## Easter eggs

- Statistics

  | Language         | Files | Lines | Blanks | Comments | Code | Complexity |
  | ---------------- | ----: | ----: | -----: | -------: | ---: | ---------: |
  | _C_              |     4 |   458 |     34 |       58 |  366 |         33 |
  | `test_maze.c`    |       |   225 |      9 |        0 |  216 |          4 |
  | `sol.maze.c`     |       |   141 |     15 |       28 |   98 |         24 |
  | `maze.c`         |       |    84 |      8 |       30 |   46 |          5 |
  | `main.c`         |       |     8 |      2 |        0 |    6 |          0 |
  | _C Header_       |     1 |    33 |      3 |       19 |   11 |          0 |
  | `maze.h`         |       |    33 |      3 |       19 |   11 |          0 |
  | _CMake_          |     1 |    25 |      4 |        6 |   15 |          2 |
  | `CMakeLists.txt` |       |    25 |      4 |        6 |   15 |          2 |
  | **Total**        |     6 |   516 |     41 |       83 |  392 |         35 |

- Majority of the line count in solution is caused by the formatting :)
- Included headers can be interpreted as hints, same goes for the unimplemented
  `static` functions which you can use, but **are not required**.
- Given `CMakeLists.txt` will generate 2 binaries, `test_maze` and `maze`.
  - `test_maze` runs the tests you are given.
  - `maze` runs the `main.c`, where you can debug, print mazes and whatever else
    you want.
- I keep only one copy of `cut.h` in my repository, so you need to download it from
  [here](https://gitlab.fi.muni.cz/pb071/cut/-/jobs/159010/artifacts/file/1header/cut.h) and place it into the directory where you have your source code.
  - Or you can use the one you have from the latest homework, git will keep it
    only once, so it doesn't take up more space.
- I would recommend cloning this repository and copying the `maze` directory to
  your own repository, since there are multiple files and it may be easier for you.

In case you have any questions, feel free to reach out to me.

## Submitting

For submitting the bonus assignment you can follow the same procedure as for
submitting the homeworks, that is:

1. On branch `main` add the provided skeleton.
2. Checkout new branch `seminar-bonus-04`.
3. Add your solution to the newly created branch.
4. Create a MR to the `main` branch with me (`@xfocko`) as the reviewer.