Lua曼哈顿距离：网格移动的距离选择

-- 错误：八向斜走地图用曼哈顿估距，步数虚高
local function dist(a, b)
    return math.abs(a.x - b.x) + math.abs(a.y - b.y)
end

local function manhattan(a, b)
    return math.abs(a.x - b.x)
        + math.abs(a.y - b.y)
end
local function chebyshev(a, b)
    return math.max(math.abs(a.x - b.x),
        math.abs(a.y - b.y))
end
local a, b = {x = 1, y = 2}, {x = 4, y = 6}
local label = panel:getChildByName("distText")
label:setString(manhattan(a, b)
    .. "/" .. chebyshev(a, b))