From c4d07ccc686ba834151431d1fbd3cf35fe2f3b06 Mon Sep 17 00:00:00 2001
From: Brett Parker <iDunno@sommitrealweird.co.uk>
Date: Sun, 6 Dec 2020 17:23:35 +0000
Subject: [PATCH] First attempt
---
day3/wires.sh | 235 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 235 insertions(+)
create mode 100644 day3/wires.sh
diff --git a/day3/wires.sh b/day3/wires.sh
new file mode 100644
index 0000000..a28765a
--- /dev/null
+++ b/day3/wires.sh
@@ -0,0 +1,235 @@
+#!/bin/bash
+
+set -u
+set -e
+
+# these wires should give 6
+#wire_1=(R8 U5 L5 D3)
+#wire_2=(U7 R6 D4 L4)
+
+# these wires should get 159
+#wire_1=(R75 D30 R83 U83 L12 D49 R71 U7 L72)
+#wire_2=(U62 R66 U55 R34 D71 R55 D58 R83)
+
+# these wires should get 135
+wire_1=(R98 U47 R26 D63 R33 U87 L62 D20 R33 U53 R51)
+wire_2=(U98 R91 D20 R16 D67 R40 U7 R15 U6 R7)
+
+# read in data from file instead
+#exec 3<input.txt
+#IFS="," read -u 3 -a wire_1
+#IFS="," read -u 3 -a wire_2
+
+get_min_max() {
+ local -n wire=$1
+ horz_min=0
+ horz_max=0
+ vert_min=0
+ vert_max=0
+ cur_horz=0
+ cur_vert=0
+ for instruction in "${wire[@]}"; do
+ direction=${instruction:0:1}
+ amount=${instruction:1}
+ case $direction in
+ U)
+ cur_vert=$((cur_vert+$amount))
+ if [ $cur_vert -gt $vert_max ]; then
+ vert_max=$cur_vert
+ fi
+ ;;
+ D)
+ cur_vert=$((cur_vert-$amount))
+ if [ $cur_vert -lt $vert_min ]; then
+ vert_min=$cur_vert
+ fi
+ ;;
+ R)
+ cur_horz=$((cur_horz+$amount))
+ if [ $cur_horz -gt $horz_max ]; then
+ horz_max=$cur_horz
+ fi
+ ;;
+ L)
+ cur_horz=$((cur_horz-$amount))
+ if [ $cur_horz -lt $horz_min ]; then
+ horz_min=$cur_horz
+ fi
+ ;;
+ esac
+ done
+
+ echo "$horz_min,$horz_max,$vert_min,$vert_max"
+}
+
+trace_wire() {
+ local -n w=$1
+ local -n b=$2
+ local -n c=$3
+ min_left=$4
+ cur_vert=0
+ cur_horz=0
+ moved=0
+ last_replace_char="-"
+
+ for operation in "${w[@]}"; do
+ direction=${operation:0:1}
+ amount=${operation:1}
+ case $direction in
+ U)
+ operator=+
+ ;;
+ D)
+ operator=-
+ ;;
+ L)
+ operator=-
+ ;;
+ R)
+ operator=+
+ ;;
+ esac
+
+ case $direction in
+ U|D)
+ last_replace_char="|"
+ offset=$((0-$min_left))
+ offset=$((offset+$cur_horz))
+ for (( moved=1; moved <= $amount; moved++ )); do
+ cur_vert=$((cur_vert${operator}1))
+ cur_line=${b[$cur_vert]}
+ cur_char=${cur_line:$offset:1}
+ replace_char="|"
+ if [ $cur_char = "-" ] || [ $cur_char = "|" ]; then
+ replace_char="X"
+ c+=($cur_horz,$cur_vert)
+ fi
+ if [ $moved -eq $amount ]; then
+ replace_char="+"
+ fi
+ if [ $cur_vert -eq 0 ] && [ $cur_horz -eq 0 ]; then
+ replace_char='o'
+ fi
+ new_line="${cur_line:0:$((offset))}${replace_char}${cur_line:$((offset+1))}"
+ b[$cur_vert]=$new_line
+ done
+ ;;
+ L|R)
+ last_replace_char="-"
+ # this could change multiple characters in the line
+ for (( moved=1; moved <= $amount; moved++ )); do
+ cur_horz=$((cur_horz${operator}1))
+ offset=$((0-$min_left))
+ offset=$((offset+$cur_horz))
+ cur_line=${b[$cur_vert]}
+ cur_char=${cur_line:$offset:1}
+ replace_char="-"
+ if [ $cur_char = "-" ] || [ $cur_char = "|" ]; then
+ replace_char="X"
+ c+=($cur_horz,$cur_vert)
+ fi
+ if [ $moved -eq $amount ]; then
+ replace_char="+"
+ fi
+ if [ $cur_vert -eq 0 ] && [ $cur_horz -eq 0 ]; then
+ replace_char='o'
+ fi
+ new_line="${cur_line:0:$((offset))}${replace_char}${cur_line:$((offset+1))}"
+ b[$cur_vert]=$new_line
+ done
+ ;;
+ esac
+ done
+
+ cur_line=${b[$cur_vert]}
+ offset=$((0-$min_left))
+ offset=$((offset+$cur_horz))
+ if [ ${cur_line:$offset:1} != 'X' ]; then
+ new_line="${cur_line:0:$((offset))}${last_replace_char}${cur_line:$((offset+1))}"
+ b[$cur_vert]=$new_line
+ fi
+ echo
+}
+
+make_board() {
+ local -n mm=$1
+ local -n b=$2
+
+ min_horz=${mm[0]}
+ if [ $min_horz -gt 0 ]; then
+ min_horz=0
+ fi
+
+ min_vert=${mm[2]}
+ if [ $min_vert -gt 0 ]; then
+ min_vert=0
+ fi
+
+ max_horz=${mm[1]}
+ total_horz=$(($max_horz - $min_horz))
+
+ max_vert=${mm[3]}
+
+ cur_vert=${min_vert}
+ blank_string=$(printf ".%.0s" $(eval echo '{0..'$total_horz'}'))
+ while [[ $cur_vert -le ${max_vert} ]]; do
+ if [[ $cur_vert -eq 0 ]]; then
+ offset=$((0-${mm[0]}))
+ line="${blank_string:0:$offset}o${blank_string:$((offset+1))}"
+ b[$cur_vert]=$line
+ else
+ b[$cur_vert]=$blank_string
+ fi
+ cur_vert=$((cur_vert+1))
+ done
+}
+
+echo "Getting board boundaries"
+IFS="," read -a min_max < <(get_min_max wire_1)
+IFS="," read -a min_max_2 < <(get_min_max wire_2)
+
+# do the minimums first
+for pos in 0 2; do
+ if [ ${min_max[$pos]} -gt ${min_max_2[$pos]} ]; then
+ min_max[$pos]=${min_max_2[$pos]}
+ fi
+done
+
+# now the maximums
+for pos in 1 3; do
+ if [ ${min_max[$pos]} -lt ${min_max_2[$pos]} ]; then
+ min_max[$pos]=${min_max_2[$pos]}
+ fi
+done
+
+echo " ${min_max[@]}"
+
+# we now know exactly how big the grid is, which is handy, as we'll use it to do offsets
+declare -A board
+declare -a cross_wires
+echo "Building board"
+make_board min_max board
+echo "Tracing first wire"
+trace_wire wire_1 board cross_wires ${min_max[0]}
+echo "Tracing second wire"
+trace_wire wire_2 board cross_wires ${min_max[0]}
+
+for (( a=${min_max[3]}; a>=${min_max[2]}; a-- )); do
+ echo ${board[$a]}
+done
+
+echo "Wires cross at:"
+min_distance=-1
+for cross in "${cross_wires[@]}"; do
+ echo " $cross"
+ horz=${cross%,*}
+ horz=${horz//-/}
+ vert=${cross#*,}
+ vert=${vert//-/}
+ distance=$((horz+$vert))
+ if [ $min_distance -lt 0 ] || [ $min_distance -gt $distance ]; then
+ min_distance=$distance
+ fi
+done
+
+echo Min distance: $min_distance
--
2.39.5