Chess Validator

A company that specializes in building mediocre games for social networking platforms has offered you a fistful of cash in the form of a one percent profit sharing agreement and free pizza. All you need to do is prove that you're the kind of rockstar programmer they need on staff by taking a simple test. Because you know that you're exactly the sort of ninja frogman devops superstar that they're looking for, you decide to give it a shot.

Your task is to create a Chess move validator: given a list of moves and a board, you are expected to determine whether each move is LEGAL or ILLEGAL. Some sample input and output files are provided to make this task a little bit easier for you to work on.

The Board

The board is represented in the simple ASCII format shown below:

bR bN bB bQ bK bB bN bR
bP bP bP bP bP bP bP bP
-- -- -- -- -- -- -- --
-- -- -- -- -- -- -- --
-- -- -- -- -- -- -- --
-- -- -- -- -- -- -- --
wP wP wP wP wP wP wP wP
wR wN wB wQ wK wB wN wR

Each piece is represented by two characters. The first character represents the player's color, and the second character represents the rank of the piece. Empty squares are represented by --.

Evaluating Moves

Moves are listed using coordinates similar to algebraic chess notation, but start and ending positions are provided explicitly for each move to avoid the need to resolve ambiguities. One move is listed per line in the moves file, as shown below:

a2 a3
a2 a4
a2 a5
a7 a6
a7 a5
a7 a4
a7 b6
b8 a6
b8 c6
b8 d7
e2 e3
e3 e2

Each move should be evaluated independently against the provided board layout. The purpose of your validator will be to determine whether a given move is legal based on the initial board state: it is not meant to evaluate a sequence of moves.

While the simple_moves.txt file only checks some basic pawn and knight moves, the complex_moves.txt exercises most of the kinds of moves you would find in an ordinary chess game, as well as various forms of invalid moves. While you are expected to test for whether a move would be illegal due to creating a check condition, you can assume that no moves involve castling or en-passant conditions.

Expected Output

For each move in your input file, there should be a corresponding line in your output file which indicates whether the move was LEGAL or ILLEGAL. For example, given the previously shown board (simple_board.txt) and move list (simple_moves.txt), your validator should output the following results:

LEGAL
LEGAL
ILLEGAL
LEGAL
LEGAL
ILLEGAL
ILLEGAL
LEGAL
LEGAL
ILLEGAL
LEGAL
ILLEGAL

simple_board.txt

bR bN bB bQ bK bB bN bR
bP bP bP bP bP bP bP bP
-- -- -- -- -- -- -- --
-- -- -- -- -- -- -- --
-- -- -- -- -- -- -- --
-- -- -- -- -- -- -- --
wP wP wP wP wP wP wP wP
wR wN wB wQ wK wB wN wR

simple_moves.txt

a2 a3
a2 a4
a2 a5
a7 a6
a7 a5
a7 a4
a7 b6
b8 a6
b8 c6
b8 d7
e2 e3
e3 e2

simple_results.txt

LEGAL
LEGAL
ILLEGAL
LEGAL
LEGAL
ILLEGAL
ILLEGAL
LEGAL
LEGAL
ILLEGAL
LEGAL
ILLEGAL

complex_board.txt

bK -- -- -- -- bB -- --
-- -- -- -- -- bP -- --
-- bP wR -- wB -- bN --
wN -- bP bR -- -- -- wP
-- -- -- -- wK wQ -- wP
wR -- bB wN wP -- -- --
-- wP bQ -- -- wP -- --
-- -- -- -- -- wB -- --

complex_moves.txt

b2 b3
f2 b7
b4 a8
a8 g5
b2 b4
h7 f6
e3 b1
b7 e4
b2 b5
g7 g2
f7 f8
g7 e8
f5 g5
f7 f6
c3 a2
e1 c1
f7 f5
g8 c6
b2 d5
f7 f4
f6 f3
c5 f4
b6 a5
c3 d7
b2 f6
e4 d8
d2 g6
b2 c3
a3 g5
h6 e8
d3 b5
d6 f3
c5 c4
f6 a3
b7 c1
f1 f1
b6 b4
a7 e5
b6 c5
c2 e7
d4 f5
a7 g8
a7 d1
c5 b4
c4 e3
h4 h3
b5 b2
b2 g4
h3 h4
h8 d3
h8 h7
h2 h3
e8 c4
a3 a1
d3 b5
a3 a1
d5 d3
d5 f5
b4 f6
d5 g2
c8 d4
d5 b5
c6 d5
f3 b5
a1 g6
g6 e5
d3 e6
g6 a7
g6 h4
c6 d8
a3 h8
g8 f8
c7 f2
d3 c4
a5 a4
a5 b5
f1 a8
c2 g1
e5 a4
h5 f1
e6 g4
g5 h2
c3 b2
h2 c7
e6 f3
c3 c4
f1 c4
b3 a6
c4 b3
c1 h6
a5 c5
f4 f7
c2 c6
f6 g2
d2 a1
e4 a3
c2 d3
a8 c6
d6 d1
c2 e4
d6 g2
a6 a7
c2 c4
a8 a7
c4 d3
c3 h5
b4 c7
e6 d5
b6 d6
e5 f8
f1 f6
a8 a6
a8 c6
e4 e5
h2 a5
c8 e1
e3 h2
f3 h3