import static java.util.stream.IntStream.rangeClosed

class Superpermutation {
    final static int nMax = 12

    static char[] superperm
    static int pos
    static int[] count = new int[nMax]

    static int factSum(int n) {
        return rangeClosed(1, n)
            .map({ m -> rangeClosed(1, m).reduce(1, { a, b -> a * b }) }).sum()
    }

    static boolean r(int n) {
        if (n == 0) {
            return false
        }

        char c = superperm[pos - n]
        if (--count[n] == 0) {
            count[n] = n
            if (!r(n - 1)) {
                return false
            }
        }
        superperm[pos++] = c
        return true
    }

    static void superPerm(int n) {
        String chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"

        pos = n
        superperm = new char[factSum(n)]

        for (int i = 0; i < n + 1; i++) {
            count[i] = i
        }
        for (int i = 1; i < n + 1; i++) {
            superperm[i - 1] = chars.charAt(i)
        }

        while (r(n)) {
        }
    }

    static void main(String[] args) {
        for (int n = 0; n < nMax; n++) {
            superPerm(n)
            printf("superPerm(%2d) len = %d", n, superperm.length)
            println()
        }
    }
}