#!/bin/bash
# I, Ian Kelling, follow the GNU license recommendations at
# https://www.gnu.org/licenses/license-recommendations.en.html. They
# recommend that small programs, < 300 lines, be licensed under the
# Apache License 2.0. This file contains or is part of one or more small
# programs. If a small program grows beyond 300 lines, I plan to switch
# its license to GPL.

# Copyright 2024 Ian Kelling

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

source /a/bin/bash-bear-trap/bash-bear

e () {
    printf "%s\n" "$*"
}


prefix=$1
suffix=$2

# print number
pn() {
  for n; do
    e $prefix$n$suffix
  done
}

# level 1 numbers
l1=(2 3 8 9)

# level 2 numbers
l2=(4 7)

l12=( ${l1[@]} ${l2[@]} )

t1() {

  pn ${l1[@]}
}

t2() {

  pn ${l2[@]}
}

declare -A used
t3() {
  for d1 in ${l1[@]}; do
    for d2 in ${l1[@]}; do
      if (( d1 == d2 )); then continue; fi
      pn $d1$d2
      used[$d1$d2]=t
    done
  done
}

t4() {
  for d1 in ${l12[@]}; do
    for d2 in ${l12[@]}; do
      if (( d1 == d2 )); then continue; fi
      if [[ ${used[$d1$d2]} ]]; then continue; fi
      pn $d1$d2
      used[$d1$d2]=t
    done
  done | sort -n
}

for t in {1..4}; do
  e tier $t
  t$t
done