require "table2"
local fmt = require "fmt"

local function spiral_matrix(n)
    local m = table.create(n)
    for i = 1, n do m[i] = table.rep(n, 0) end
    local dx, dy = {0, 1, 0, -1}, {1, 0, -1, 0}
    local x, y, c = 0, -1, 1
    for i = 0, n + n - 2 do
        for j = 0, (n + n - i) // 2  - 1 do
            x += dx[i % 4 + 1]
            y += dy[i % 4 + 1]
            m[x + 1][y + 1] = c
            c += 1
        end
    end
    return m
end

for spiral_matrix(5) as a do fmt.tprint("%2d", a, #a) end