From 51c5bd4e54ddb0a8a41255b58ff8ffa620db0b99 Mon Sep 17 00:00:00 2001
From: Maximilian Friedersdorff <max@friedersdorff.com>
Date: Mon, 13 Dec 2021 22:00:48 +0000
Subject: [PATCH] Finish day 12 and 13

---
 12_1.py | 29 +++++++++++++++++++++++++++++
 12_2.py | 30 ++++++++++++++++++++++++++++++
 13_1.py | 43 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 102 insertions(+)
 create mode 100644 12_1.py
 create mode 100644 12_2.py
 create mode 100644 13_1.py

diff --git a/12_1.py b/12_1.py
new file mode 100644
index 0000000..bd0dc70
--- /dev/null
+++ b/12_1.py
@@ -0,0 +1,29 @@
+""" Count number of paths through caves """
+from collections import defaultdict
+
+def walk_from_node(current_node, path_taken_so_far):
+    possible_paths = []
+    for node in caves[current_node]:
+        if node == "end":
+            possible_paths.append(path_taken_so_far + ["end"])
+        elif node == node.lower() and node in path_taken_so_far:
+            pass
+        else:
+            possible_paths += walk_from_node(node, path_taken_so_far + [current_node])
+
+    return possible_paths
+
+caves = defaultdict(set)
+
+with open("12_input.txt") as f:
+    for line in f:
+        node_a, node_b = line.strip().split("-")
+
+        caves[node_a].add(node_b)
+        caves[node_b].add(node_a)
+
+walked_paths = walk_from_node("start", [])
+print(len(walked_paths))
+
+filtered_walked_paths = [path for path in walked_paths if path[-1] == "end"]
+print(len(filtered_walked_paths))
diff --git a/12_2.py b/12_2.py
new file mode 100644
index 0000000..ff930e9
--- /dev/null
+++ b/12_2.py
@@ -0,0 +1,30 @@
+""" Count number of paths through caves """
+import pprint
+from collections import defaultdict
+
+def walk_from_node(current_node, path_taken_so_far, visited_small_cave_twice=False):
+    possible_paths = []
+    for node in caves[current_node]:
+        if node == "start":
+            pass
+        elif node == "end":
+            possible_paths.append(path_taken_so_far + ["end"])
+        elif node == node.lower() and node in path_taken_so_far:
+            if not visited_small_cave_twice:
+                possible_paths += walk_from_node(node, path_taken_so_far + [current_node], True)
+        else:
+            possible_paths += walk_from_node(node, path_taken_so_far + [current_node], visited_small_cave_twice)
+
+    return possible_paths
+
+caves = defaultdict(set)
+
+with open("12_input.txt") as f:
+    for line in f:
+        node_a, node_b = line.strip().split("-")
+
+        caves[node_a].add(node_b)
+        caves[node_b].add(node_a)
+
+walked_paths = walk_from_node("start", [])
+print(len(walked_paths))
diff --git a/13_1.py b/13_1.py
new file mode 100644
index 0000000..678c3cd
--- /dev/null
+++ b/13_1.py
@@ -0,0 +1,43 @@
+""" Count the dots on slightly folded transparent paper """
+
+dots = set()
+with open("13_input.txt") as f:
+    for line in f:
+        if line.strip() == "":
+            break
+        else:
+            dots.add(tuple(int(a) for a in line.split(",")))
+
+    for fold in f:
+        direction, fold_line = fold.strip().split(" ")[2].split("=")
+        fold_line = int(fold_line)
+
+        folded_dots = set()
+        for x, y in dots:
+            if direction == "x" and x > fold_line:
+                diff = x - fold_line
+                x = fold_line - diff
+            elif direction == "y" and y > fold_line:
+                diff = y - fold_line
+                y = fold_line - diff
+
+            folded_dots.add((x, y))
+
+        dots = folded_dots
+        # break  # First part just wants the number of dots after first fold.
+
+
+
+xs, ys = list(zip(*dots))
+max_x = max(xs)
+max_y = max(ys)
+
+for j in range(max_y + 1):
+    line = []
+    for i in range(max_x + 1):
+        if (i, j) in dots:
+            line.append("#")
+        else:
+            line.append(".")
+
+    print("".join(line))
-- 
2.46.2