叠方块：一行凑齐一闪光

local holes = CountHoles(board, piece, x, y)   -- 落下后棋盘下的空洞数

fx-tetris

local Stack = {}
local KEY = { HEIGHT_W = 3, HOLE_W = 30 }

local function LandingRow(board, piece, x)
    local y = piece.y
    while not Stack.Collide(board, piece, x, y + 1) do y = y + 1 end
    return y
end

local function CountNewHoles(board, piece, x, y)
    local holes = 0
    for c = 0, #piece.m[1] - 1 do
        -- 找该列最低的实心格
        local low = -1
        for r = #piece.m - 1, 0, -1 do
            if piece.m[r + 1][c + 1] then low = r; break end
        end
        if low >= 0 then
            local gy = y + low + 1
            while gy < #board do
                if not board[gy + 1][x + c + 1] then holes = holes + 1 end
                gy = gy + 1
            end
        end
    end
    return holes
end

function Stack.Place(board, piece)
    local best, bestScore = nil, -1e9
    for x = 0, Stack.Cols - #piece.m[1] do
        if not Stack.Collide(board, piece, x, 0) then
            local y = LandingRow(board, piece, x)
            local score = -y * KEY.HEIGHT_W
                       - CountNewHoles(board, piece, x, y) * KEY.HOLE_W
            if score > bestScore then bestScore = score; best = x end
        end
    end
    return best
end

return Stack