Ecole 42ProgrammingProjects

Fillit – Packing Tetris pieces

This Ecole 42 project went faster than expected, I feel like I’m starting to get back into a productive programming mindset.

Description

Fillit is not about recoding Tetris, even if it’s still a variant of this game. This program will take a file as parameter, which contains a list of Tetriminos, and arrange them in order to create the smallest square possible.

The program

The executable “fillit” takes only one parameter, a file which contains a list of Tetriminos to assemble. This file has a very specific format (see input sample).

Input Sample:

Each tetraminos is represented with 4 lines of 4 characters, each followed by a new line. A Tetrimino is a classic piece of Tetris composed of 4 blocks. Each character must be either a block character(’#’) or an empty character (’.’). Each block of a Tetrimino must touch at least one other block on any of his 4 sides (up, down, left and right).

...#
...#
...#
...#

....
....
....
####

.###
...#
....
....

....
..##
.##.
....

....
.##.
.##.
....

....
....
##..
.##.

##..
.#..
.#..
....

....
###.
.#..
....

Output Sample:

The program displays the smallest assembled square on the standard output. To identify each Tetrimino in the square solution, a capital letter will be assigned to each Tetrimino, starting with ’A’ and increasing for each new Tetrimino.

ABBBB.
ACCCEE
AFFCEE
A.FFGG
HHHDDG
.HDD.G

Solution

The program is divided in two parts:A part that reads, validate, organize the input and a second part that solves the problem using backtracking. here is how the program works:

Reading the input and preparing the data

  • The program take the path of the input file as argument, returns usage instruction if argument is blank, error if there are more than 1 arguments.
  • The function main() calls setup(), here the buffer of the file reads 21 bytes while it counts and validate formally the block.
  • Kowning how many blocks are in the input file gen_matrices() allocates a list of size matrices (4×4) and then fill_matrices() fills it with the letters representing the different blocks.
  • The empty rows and column of the matries representig each block are removed by the functions clean_row_matrices() and clean_column_matrices(), (this is probably not the best way to do this).

Solving the problem

  • Takes the list of tetraminos and evaluates how big should be the minimum square that can hold all those pieces.
  • Generates a matrix of size min_size with the fucntion gen_row().
  • Calls the function bfs_big_fucking_solver() wich taking in the emty solution grid and the list of tetraminos solves the problem wihtout allocating any more memory trough backtracking, insertions and restorations.
  • The solution is printed by print_row(row)

Notes

The matrices starts at zero and the standard naming system is used (as shown in the image underneath). Every row is null terminated and the last row is NULL.

Matrix Notation

Example

How to guide