Day 12

12/01.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+
+declare -A transitions
+while read line; do
+  first=$(sed 's/-.*$//' <<< $line)
+  last=$(sed 's/^.*-//' <<< $line)
+  transitions[$first]=${transitions[$first]}','$last','
+  transitions[$last]=${transitions[$last]}','$first','
+done
+
+paths=()
+
+find_paths() {
+  local current_path=( ${1//,/ } )
+  local marked_caves=$2
+  local current_transitions=${transitions[${current_path[-1]}]}
+  current_transitions=( ${current_transitions//,/ } )
+  local current_transition
+  for current_transition in ${current_transitions[@]}; do
+    if [[ $current_transition == 'end' ]]; then
+      paths+=( $1','$current_transition',' )
+    elif [[ ${current_transition:0:1} == [A-Z] ]]; then
+      find_paths $1','$current_transition',' $marked_caves
+    elif ! [[ $marked_caves == *','$current_transition','* ]]; then
+      find_paths $1','$current_transition',' $marked_caves','$current_transition','
+    fi
+  done
+}
+
+find_paths ',start,' ',start,'
+
+echo ${#paths[@]}

12/02.sh

@@ -0,0 +1,35 @@
+#!/bin/bash
+
+declare -A transitions
+while read line; do
+  first=$(sed 's/-.*$//' <<< $line)
+  last=$(sed 's/^.*-//' <<< $line)
+  transitions[$first]=${transitions[$first]}','$last','
+  transitions[$last]=${transitions[$last]}','$first','
+done
+
+paths=()
+
+find_paths() {
+  local current_path=( ${1//,/ } )
+  local marked_caves=$2
+  local visited_twice=$3
+  local current_transitions=${transitions[${current_path[-1]}]}
+  current_transitions=( ${current_transitions//,/ } )
+  local current_transition
+  for current_transition in ${current_transitions[@]}; do
+    if [[ $current_transition == 'end' ]]; then
+      paths+=( $1','$current_transition',' )
+    elif [[ ${current_transition:0:1} == [A-Z] ]]; then
+      find_paths $1','$current_transition',' $marked_caves $visited_twice
+    elif ! [[ $marked_caves == *','$current_transition','* ]]; then
+      find_paths $1','$current_transition',' $marked_caves','$current_transition',' $visited_twice
+    elif [ $visited_twice -eq 0 ] && ! [[ $current_transition == 'start' ]]; then
+      find_paths $1','$current_transition',' $marked_caves 1
+    fi
+  done
+}
+
+find_paths ',start,' ',start,' 0
+
+echo ${#paths[@]}