102 lines
2.1 KiB
Bash
Executable File
102 lines
2.1 KiB
Bash
Executable File
#!/usr/bin/env bash
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#
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# aoc.bash: Advent of Code 2022, day 9
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#
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# Copyright (C) 2022 Bruno Raoult ("br")
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# Licensed under the GNU General Public License v3.0 or later.
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# Some rights reserved. See COPYING.
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#
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# You should have received a copy of the GNU General Public License along with this
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# program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
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#
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# SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
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. common.bash
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declare -a h{0..10} # h0 is head
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declare -A visited=() # keep count of visited
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declare -i last=1 # tail (last knot)
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add_pos() {
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local -n queue="$1"
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visited["${queue[0]}"/"${queue[1]}"]=1
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}
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direction() {
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local -n _dx="$1" _dy="$2"
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local dir="$3"
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(( _dx=0, _dy=0 ))
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case "$dir" in
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L) _dx=-1 ;;
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R) _dx=1 ;;
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U) _dy=1 ;;
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D) _dy=-1 ;;
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esac
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}
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do_tail() {
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local -n _h="$1" _t="$2"
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local -i dx dy sx sy
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(( dx = _h[0] - _t[0], dy = _h[1] - _t[1] ))
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(( sx = dx > 0? 1: -1 ))
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(( sy = dy > 0? 1: -1 ))
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if (( sx * dx > 1 || sy * dy > 1)); then
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(( dx > 0 )) && (( _t[0]++ ))
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(( dx < 0 )) && (( _t[0]-- ))
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(( dy > 0 )) && (( _t[1]++ ))
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(( dy < 0 )) && (( _t[1]-- ))
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fi
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}
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move_t() {
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local -i _n
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for (( _n = 0; _n < last; ++_n )); do
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do_tail "h$_n" "h$((_n + 1))"
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done
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add_pos "h$last"
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return
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}
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move_h() {
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local -i _dx="$1" _dy="$2" _m="$3" _i _n
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for ((_i = 0; _i < _m; ++_i)); do
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(( h0[0] += _dx, h0[1] += _dy ))
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move_t
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done
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}
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parse() {
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local dir moves dx dy
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(( last = $1 == 1? 1: 9 ))
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while read -r dir moves; do
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direction dx dy "$dir"
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move_h "$dx" "$dy" "$moves"
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done
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}
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part1() {
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local -n _t="h$last"
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res=${#visited[@]}
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}
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part2() {
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local -n _t="h$last"
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res=${#visited[@]}
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}
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solve() {
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local part="$1"
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add_pos "h$last"
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if ((part == 1)); then
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part1
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else
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part2
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fi
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}
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main "$@"
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exit 0
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