From 013c76a977c11f8c049152a6edb455c77caa1e9d Mon Sep 17 00:00:00 2001
From: Pierre Jeanjean <rhiobet@gmail.com>
Date: Sun, 12 Dec 2021 11:28:43 +0100
Subject: [PATCH] Day 12

---
 .gitignore |  1 +
 12/01.sh   | 32 ++++++++++++++++++++++++++++++++
 12/02.sh   | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 68 insertions(+)
 create mode 100755 12/01.sh
 create mode 100755 12/02.sh

diff --git a/.gitignore b/.gitignore
index ce5c312..d146596 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 **/input.txt
+**/example.txt
diff --git a/12/01.sh b/12/01.sh
new file mode 100755
index 0000000..33ccfca
--- /dev/null
+++ b/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 ${#paths[@]}
diff --git a/12/02.sh b/12/02.sh
new file mode 100755
index 0000000..a2aeefb
--- /dev/null
+++ b/12/02.sh
@@ -0,0 +1,35 @@
+#!/bin/bash
+
+declare -A transitions
+while read line; do
+  first=$(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[@]}