func concat[a: i64, b: i64] : i64
    let a_str: str = str.from_i64(a)
    let b_str: str = str.from_i64(b)
    let ab_str: str = str.concat(a_str, b_str)
    let out: i64 = str.parse_i64(ab_str)
    // without freeing the program works but leaks 2GB of memory :p
    mem.free(a_str)
    mem.free(b_str)
    mem.free(ab_str)
    return out

func solve[ops: array, e: array] : i64
    let n: i64 = array.size(array.nth(e, 1)) - 1
    let indices: array = []
    for i in 0..n
        array.push(indices, 0)

    while true
        let res: i64 = array.nth(array.nth(e, 1), 0)
        for i in 0..n
            let op: str = array.nth(ops, array.nth(indices, i))

            if str.equal(op, "add")
                res = res + array.nth(array.nth(e, 1), i + 1)
            else if str.equal(op, "mul")
                res = res * array.nth(array.nth(e, 1), i + 1)
            else if str.equal(op, "concat")
                res = concat(res, array.nth(array.nth(e, 1), i + 1))
        if res == array.nth(e, 0)
            return res

        let done: bool = true
        let i: i64 = n - 1

        while i >= 0
            array.set(indices, i, array.nth(indices, i) + 1)
            if array.nth(indices, i) < array.size(ops)
                done = false
                break
            array.set(indices, i, 0)
            i = i - 1
        
        if done
            return 0

func part1[equations: array] : void
    let out: i64 = 0

    for i in 0..array.size(equations)
        out = out + solve(["add", "mul"], array.nth(equations, i))

    io.println_i64(out)

func part2[equations: array] : void
    let out: i64 = 0

    for i in 0..array.size(equations)
        out = out + solve(["add", "mul", "concat"], array.nth(equations, i))

    io.println_i64(out)

func main[] : i64
    let lines: array = io.read_file("input.txt") |> str.split("\n")
    let equations: array = []

    for i in 0..array.size(lines)
        let line: str = array.nth(lines, i)
        let parts: array = str.split(line, ": ")

        let xs: array = str.split(array.nth(parts, 1), " ")
        for j in 0..array.size(xs)
            array.set(xs, j, str.parse_i64(array.nth(xs, j)))

        array.push(equations, [str.parse_i64(array.nth(parts, 0)), xs])

    part1(equations)
    part2(equations)