Day 16 part 2 (bash version)

day16/Makefile

@@ -20,7 +20,7 @@ ex1:
 	@#$(TIME) ex1-c 2020 < $(INPUT) 2>&1
 
 ex2:
-	@#$(TIME) ex1.bash 30000000 < $(INPUT) 2>&1
+	@$(TIME) ex2.bash < $(INPUT) 2>&1
 	@#$(TIME) ex1-c 30000000 < $(INPUT) 2>&1
 
 clean:

day16/README

@@ -41,8 +41,6 @@ It doesn't matter which position corresponds to which field; you can identify in
 Consider the validity of the nearby tickets you scanned. What is your ticket scanning error rate?
 
 Your puzzle answer was 21996.
-
-The first half of this puzzle is complete! It provides one gold star: *
 --- Part Two ---
 
 Now that you've identified which tickets contain invalid values, discard those tickets entirely. Use the remaining valid tickets to determine which field is which.
@@ -67,8 +65,12 @@ Based on the nearby tickets in the above example, the first position must be row
 
 Once you work out which field is which, look for the six fields on your ticket that start with the word departure. What do you get if you multiply those six values together?
 
-Answer:
+Your puzzle answer was 650080463519.
 
-Although it hasn't changed, you can still get your puzzle input.
+Both parts of this puzzle are complete! They provide two gold stars: **
+
+At this point, you should return to your Advent calendar and try another puzzle.
+
+If you still want to see it, you can get your puzzle input.
 
 You can also [Share] this puzzle.

day16/TEST2.txt

@@ -0,0 +1,11 @@
+class: 0-1 or 4-19
+row: 0-5 or 8-19
+seat: 0-13 or 16-19
+
+your ticket:
+11,12,13
+
+nearby tickets:
+3,9,18
+15,1,5
+5,14,9

day16/ex1.bash

@@ -20,6 +20,7 @@ while read -r line; do
 	elif [[ $line != "" ]]; then
 		if ((state == 2)); then
 			for i in ${line//,/ }; do
+				# shellcheck disable=SC2100
 				[[ ! -v valid[$i] ]] && res=res+i
 			done
 		fi

day16/ex2.bash

@@ -0,0 +1,90 @@
+#!/bin/bash
+#
+# ex2.bash: Advent2020 game, day 16/game 2.
+
+CMD=${0##*/}
+shopt -s extglob
+
+declare -a valid=() myticket=() keys=() values=() match=()
+declare -A position=()
+declare -i state=0 res=1 curkey=0 curticket=0
+
+while read -r line; do
+	if [[ $line =~ ^([a-z ]+)\:\ ([0-9]+)-([0-9]+)([a-z ]+)([0-9]+)-([0-9]+)$ ]]; then
+		# valid ranges
+		keys[$curkey]="${BASH_REMATCH[1]}"
+		n1=$(seq -s" " "${BASH_REMATCH[2]}" "${BASH_REMATCH[3]}")
+		n2=$(seq -s" " "${BASH_REMATCH[5]}" "${BASH_REMATCH[6]}")
+
+		for i in $n1 $n2; do
+			valid[$i]=1
+		done
+		values[$curkey]="${n1[*]} ${n2[*]}"
+		((curkey++))
+
+	elif [[ $line =~ (your ticket:|nearby tickets) ]]; then
+		# next section
+		((state++))
+	elif [[ $line =~ [0-9,]+ ]]; then
+		# shellcheck disable=SC2206
+		numbers=( ${line//,/ } )
+		case $state in
+			1)									  # my ticket
+				# shellcheck disable=SC2206
+				myticket=( ${numbers[@]} )
+				# initialize possible matches array: all
+				for ((i=0; i<curkey; ++i)); do
+					for ((j=0; j<${#numbers[@]}; ++j)); do
+						match[$j]+=" $i "
+					done
+				done
+				;;
+			2)									  # other tickets
+				#printf "ticket %d\n" "$curticket"
+				for i in ${numbers[*]}; do
+					[[ ! -v valid[$i] ]] && continue 2
+				done
+				for ((j=0; j<curkey; ++j)); do
+					for ((i=0; i<${#numbers[@]}; ++i)); do
+						num=" ${numbers[$i]} "
+						[[ " ${values[$j]} " =~ $num ]] && continue
+						match[$j]=${match[$j]// $i /}
+
+					done
+				done
+				((curticket++))
+				;;
+		esac
+	fi
+done
+
+end=0
+while ((end==0)); do
+	end=1
+	for ((i=0; i<${#match[@]}; ++i)); do
+		[[ -n ${position[$i]} ]] && continue
+		# shellcheck disable=SC2206
+		array=( ${match[$i]} )
+		if (( ${#array[@]} == 1 )); then
+			cur=${array[0]}
+			position[$i]=$cur
+			for ((j=0; j<${#match[@]}; ++j)); do
+				((j != i)) && match[$j]=${match[$j]// $cur /}
+			done
+			end=0
+			break
+		fi
+	done
+done
+
+for ((i=0; i<${#keys[@]}; ++i )); do
+	if [[ ${keys[$i]} =~ "departure" ]]; then
+		pos=${match[$i]}
+		(( res *= ${myticket[$pos]} ))
+	fi
+done
+
+
+printf "%s : res=%d\n" "$CMD" "$res"
+
+exit 0