rename repo, subdir for yearly challenges

2020/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