SUB perms (n)
    DIM a(0 TO n - 1), c(0 TO n - 1)

    FOR j = 0 TO n - 1
        a(j) = j + 1
        PRINT a(j);
    NEXT j
    PRINT

    i = 0
    WHILE i < n
        IF c(i) < i THEN
            IF (i AND 1) = 0 THEN
                SWAP a(0), a(i)
            ELSE
                SWAP a(c(i)), a(i)
            END IF
            FOR j = 0 TO n - 1
                PRINT a(j);
            NEXT j
            PRINT
            c(i) = c(i) + 1
            i = 0
        ELSE
            c(i) = 0
            i = i + 1
        END IF
    WEND
END SUB

perms(4)