The Snail Game

By: G.A.JAGUAR

Description

Given a bidimentional array n * m, develop a function that generates an unidimentional array 1 * nm which elements correspond with original array's elements obtained by following a clockwise snail trajectory.

Example

Input:

[
    [ 1, 2, 3 ],
    [ 4, 5, 6 ],
    [ 7, 8, 9 ],
]

Output:

[ 1, 2, 3, 6, 9, 8, 7, 4, 5 ]

Solution

There is a four basic movements that can be performed by the snail: right, down, left and up (in that order, I mean clockwise). Each lap of this curious animal will reduce the distance by one.

This movements will be repeated until the snail reaches the last element of original array.

On each step of our dear friend, it will store the current value into a new array, at the end it will return this last one.

Algorithm

1. Begin.
2. Read array
3. Verify if array has two rows at least.
4. Verify if each row has two columns at least.
5. Verify if all rows are of the same size.
6. Verify if all items are integers.
7. Initialize result array.
8. Initialize rows with the number of rows of array.
9. Initialize columns with the number of columns of array.
10. Calculate total = rows * columns.
11. Initialize lap counter at 0.
12. Repeat next 4 steps until result size = total then jump to step 17:
13. Move to right and store into result the current value on every step.
14. Move to down and store into result the current value on every step.
15. Move to left and store into result the current value on every step.
16. Move to up and store into result the current value on every step.
17. Add 1 to lap.
18. Return result.
19. End.

Code

A implementation of this algorithm is available here.

Build

In order to it works properly, first copy .env.example file as .env.

Docker

Fast setup (only linux os)

# build docker container.
sh scripts/install

# execute the script.
sh scripts/run

Manual

# create a docker image
docker-compose build

# build for execution
docker-compose run --rm dev

Local

# on linux os:
python3 app/main.py

# on widows os:
py app\main.py

Screenshots