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advent-of-code/2022/day06/aoc.bash

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#!/usr/bin/env bash
#
# aoc.bash: Advent of Code 2022, day 6
#
# Copyright (C) 2022 Bruno Raoult ("br")
# Licensed under the GNU General Public License v3.0 or later.
# Some rights reserved. See COPYING.
#
# You should have received a copy of the GNU General Public License along with this
# program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
#
# SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
. common.bash
declare -a stacks=() rules=()
parse() {
local -i _queue _state=1
local _input
local -a _parse
local cur=""
local -i lcur=0 i
read -r _input
len=${#_input}
lcur=0
for (( i = 0; i < len - 4; ++i )); do
echo
nextc=${_input:i:1} # get next char
printf "next=%s cur=%s lcur=%d\n" "$nextc" "$cur" "$lcur"
for ((j = 0; j < lcur; ++j)); do # compare with previous ones
printf "compare %s with %d:%s\n" "$nextc" "$j" "${cur:j:1}"
if [[ $nextc == "${cur:j:1}" ]]; then
cur=${cur:j+1}$nextc
(( lcur = lcur - (j + 1) + 1))
printf "\t-> equal cur=%d:%s" "$lcur" "$cur"
continue 2
fi
done
cur+=$nextc
((lcur++))
((lcur == 4)) && break
done
echo "$cur" $((i + 1))
}
solve() {
local -i _part="$1" _i=0 _j=0 _nb _from _to
local -a _rule
for ((; _i < ${#rules[@]}; ++_i )); do
read -ra _rule <<< "${rules[$_i]}"
(( _nb = _rule[0], _from = _rule[1] - 1, _to = _rule[2] - 1 ))
if ((_part == 1)); then
# move elements one by one
for ((_j = 0; _j < _nb; ++_j)); do
stacks[$_to]="${stacks[$_from]:0:1}${stacks[$_to]}"
stacks[$_from]=${stacks[$_from]:1}
done
else
# move elements by block
stacks[$_to]="${stacks[$_from]:0:_nb}${stacks[$_to]}"
stacks[$_from]=${stacks[$_from]:_nb}
fi
done
printf -v res "%c" "${stacks[@]}"
}
main "$@"
exit 0