136 lines
3.2 KiB
Bash
Executable File
136 lines
3.2 KiB
Bash
Executable File
#!/usr/bin/env bash
|
|
#
|
|
# aoc.bash: Advent of Code 2022, day 8
|
|
#
|
|
# 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 trees=() # trees height
|
|
declare -Ai visible=() # visible if set
|
|
declare -i size
|
|
|
|
parse() {
|
|
readarray -t trees
|
|
size=${#trees[@]}
|
|
}
|
|
|
|
# height - return height of a tree
|
|
# $1: reference of return value
|
|
# $2, $3: x, y
|
|
# x is column, y is row
|
|
height() {
|
|
local -n _ret="$1"
|
|
_ret=${trees[$3]:$2:1}
|
|
}
|
|
|
|
check_visible() {
|
|
local -n _max="$1"
|
|
local -i _x="$2" _y="$3" _c
|
|
|
|
height _c "$x" "y"
|
|
if (( _c > _max )); then
|
|
(( visible[$x-$y]++, _max=_c ))
|
|
(( _max == 9 )) && return 1
|
|
fi
|
|
return 0
|
|
}
|
|
|
|
part1() {
|
|
declare -ig res
|
|
local -i x y max
|
|
|
|
for ((y = 1; y < size -1; ++y)); do # to east
|
|
height max 0 "$y"
|
|
(( max == 9 )) && continue
|
|
for ((x = 1; x < size -1; ++x)); do
|
|
check_visible max "$x" "$y" || break
|
|
done
|
|
done
|
|
for ((y = 1; y < size -1; ++y)); do # to west
|
|
height max $((size - 1)) "$y"
|
|
(( max == 9 )) && continue
|
|
for ((x = size - 2; x > 0; --x)); do
|
|
check_visible max "$x" "$y" || break
|
|
done
|
|
done
|
|
for ((x = 1; x < size -1; ++x)); do # to south
|
|
height max "$x" 0
|
|
(( max == 9 )) && continue
|
|
for ((y = 1; y < size -1; ++y)); do
|
|
check_visible max "$x" "$y" || break
|
|
done
|
|
done
|
|
for ((x = 1; x < size -1; ++x)); do # to north
|
|
height max "$x" $((size - 1))
|
|
(( max == 9 )) && continue
|
|
for ((y = size - 2; y > 0; --y)); do
|
|
check_visible max "$x" "$y" || break
|
|
done
|
|
done
|
|
(( res = ${#visible[@]} + size * 4 - 4 ))
|
|
}
|
|
|
|
check_tree() {
|
|
local -n res=$1
|
|
local -i X="$2" Y="$3" c x y h
|
|
local -ai vis=()
|
|
|
|
height h "$X" "$Y"
|
|
for ((x = X + 1; x < size ; ++x)); do # east
|
|
height c "$x" "Y"
|
|
(( vis[0]++ ))
|
|
((c >= h)) && break
|
|
done
|
|
for ((x = X - 1; x >= 0; --x)); do # west
|
|
height c "$x" "Y"
|
|
(( vis[1]++ ))
|
|
((c >= h)) && break
|
|
done
|
|
for ((y = Y + 1; y < size; ++y)); do # south
|
|
height c "$X" "$y"
|
|
(( vis[2]++ ))
|
|
((c >= h)) && break
|
|
done
|
|
for ((y = Y - 1; y >= 0; --y)); do # north
|
|
height c "$X" "$y"
|
|
(( vis[3]++ ))
|
|
((c >= h)) && break
|
|
done
|
|
# shellcheck disable=1102
|
|
res=$(( "${vis[@]/%/ *}" 1))
|
|
}
|
|
|
|
|
|
part2() {
|
|
local -ig res=0
|
|
local -i tmp=1 x y
|
|
|
|
for ((x = 1; x < size - 1; ++x)); do
|
|
for ((y = 1; y < size - 1; ++y)); do
|
|
check_tree tmp "$x" "$y"
|
|
if ((tmp > res)); then
|
|
((res = tmp))
|
|
fi
|
|
done
|
|
done
|
|
}
|
|
|
|
solve() {
|
|
if ((part == 1)); then
|
|
part1
|
|
else
|
|
part2
|
|
fi
|
|
}
|
|
|
|
main "$@"
|
|
exit 0
|