def is_valid()

in gym/envs/toy_text/frozen_lake.py [0:0]

• 18 lines of code
• 10 McCabe index (conditional complexity)

def is_valid(board: List[List[str]], max_size: int) -> bool:
    frontier, discovered = [], set()
    frontier.append((0, 0))
    while frontier:
        r, c = frontier.pop()
        if not (r, c) in discovered:
            discovered.add((r, c))
            directions = [(1, 0), (0, 1), (-1, 0), (0, -1)]
            for x, y in directions:
                r_new = r + x
                c_new = c + y
                if r_new < 0 or r_new >= max_size or c_new < 0 or c_new >= max_size:
                    continue
                if board[r_new][c_new] == "G":
                    return True
                if board[r_new][c_new] != "H":
                    frontier.append((r_new, c_new))
    return False