require "utils"

function calValidOptions(b, x, y)
    if b[x][y] ~= 0 then return {} end
    local elm
    local u = {}
    local v = {}
    for i = 1, 9 do
        elm = b[x][i]
        if elm ~= 0 and find(u, elm) == 0 then
            table.insert(u, elm)
        end
        elm = b[i][y]
        if elm ~= 0 and find(u, elm) == 0 then
            table.insert(u, elm)
        end
    end
    local xc = ((x - 1) // 3) * 3
    local yc = ((y - 1) // 3) * 3
    for i = 1, 3 do
        for j = 1, 3 do
            elm = b[i+xc][j+yc]
            if elm ~= 0 and find(u, elm) == 0 then
                table.insert(u, elm)
            end
        end
    end
    for i = 1, 9 do
        if find(u, i) == 0 then table.insert(v, i) end
    end
    return v
end

function buildSearchSpace(b)
    local s = {}
    for i = 1, 9 do
        s[i] = {}
        for j = 1, 9 do
            s[i][j] = calValidOptions(b, i, j)
        end
    end
    return s
end