2022 day 9, Bash part 1

2022/day09/aoc.bash

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+#!/usr/bin/env bash
+#
+# aoc.bash: Advent of Code 2022, day 9
+#
+# 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 -i xh=0 yh=0 xt=0 yt=0
+declare -A visited=()
+
+add_pos() {
+    (( visited["$1-$2"]++ ))
+}
+
+direction() {
+    local -n _dx="$1" _dy="$2"
+    local dir="$3"
+    (( _dx=0, _dy=0 ))
+    case "$dir" in
+        L) _dx=-1 ;;
+        R) _dx=1 ;;
+        U) _dy=1 ;;
+        D) _dy=-1 ;;
+    esac
+}
+
+move_t() {
+    local -i dx dy sx sy
+
+    (( dx = xh - xt, dy = yh - yt ))
+    (( sx = dx > 0? 1: -1 ))
+    (( sy = dy > 0? 1: -1 ))
+
+    #printf " [move_t: dx=%d dy=%d " "$dx" "$dy"
+    if (( sx * dx > 1 || sy * dy > 1)); then
+        (( dx > 0 )) && (( xt++ ))
+        (( dx < 0 )) && (( xt-- ))
+        (( dy > 0 )) && (( yt++ ))
+        (( dy < 0 )) && (( yt-- ))
+    fi
+    #printf "xt=%d yt=%d] " "$xt" "$yt"
+    add_pos "$xt" "$yt"
+}
+
+move_h() {
+    local -i dx="$1" dy="$2" n="$3" i
+    #printf "\tmove_h dx=%d dy=%d n=%d\n" "$dx" "$dy" "$n"
+    for ((i = 0; i < n; ++i)); do
+        (( xh += dx, yh += dy ))
+        #printf -- "(%d,%d)" "$xh" "$yh"
+        move_t
+        #printf -- "/(%d,%d)\n" "$xt" "$yt"
+    done
+}
+
+parse() {
+    local dir moves dx dy
+
+    while read -r dir moves; do
+        #printf "(%d,%d)/(%d,%d) %s/%d\n" "$xh" "$yh" "$xt" "$yt" "$dir" "$moves"
+        direction dx dy "$dir"
+        #printf "\tafter direction dx=%d dy=%d\n" "$dx" "$dy"
+        move_h "$dx" "$dy" "$moves"
+        #printf "\th: (%d,%d)/(%d,%d)\n" "$xh" "$yh" "$xt" "$yt"
+        add_pos "$xt" "$yt"
+    done
+}
+
+part1() {
+    declare -ig res
+    parse
+    #echo FINAL
+    #echo "${!visited[@]}"
+    res=${#visited[@]}
+}
+
+part2() {
+    :
+}
+
+solve() {
+    add_pos 0 0
+    if ((part == 1)); then
+        part1
+    else
+        part2
+    fi
+}
+
+main "$@"
+exit 0