From 052a11762c6ab5af7f7e49c0948912e0eec6f52b Mon Sep 17 00:00:00 2001
From: Johannes <freelon@gmx.net>
Date: Sat, 21 Dec 2024 09:31:02 +0100
Subject: [PATCH] day 20 part 1 python

---
 day20.py | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 day20.py

diff --git a/day20.py b/day20.py
new file mode 100644
index 0000000..15094b7
--- /dev/null
+++ b/day20.py
@@ -0,0 +1,45 @@
+def parse_input(input: list[str]):
+    l = [(x, y) for (y, line) in enumerate(input) for (x, c) in enumerate(line) if c == '#']
+    start = [(x, y) for (y, line) in enumerate(input) for (x, c) in enumerate(line) if c == 'S'][0]
+    goal = [(x, y) for (y, line) in enumerate(input) for (x, c) in enumerate(line) if c == 'E'][0]
+    w = max([x for (x, y) in l])
+    h = max([y for (x, y) in l])
+    return l, w, h, start, goal
+
+
+def sp(points, w, h, start, goal):
+    visited = dict()
+    (sx, sy) = start
+    stack = [(sx, sy, 0)]
+    while len(stack) > 0:
+        (x, y, c) = stack.pop(0)
+        if (x, y) == goal:
+            return c
+
+        if (x, y) in visited:
+            continue
+        visited[(x, y)] = c
+
+        for (a, b) in [(x+nx, y+ny) for (nx, ny) in [(0, 1), (1, 0), (0, -1), (-1, 0)]]:
+            if 0 <= a <= w and 0 <= b <= w and (a, b) not in points:
+                stack.append((a, b, c + 1))
+
+    return None
+
+
+source = "input/day20.txt"
+with open(source, 'r') as f:
+    data = f.read()
+
+(points, w, h, start, goal) = parse_input(data.strip().split('\n'))
+bottomline = sp(set(points), w, h, start, goal)
+print(bottomline)
+atleast100 = 0
+for p in points:
+    remains = [x for x in points if p != x]
+    pathlength = sp(set(remains), w, h, start, goal)
+    if bottomline - pathlength >= 100:
+        atleast100 += 1
+
+
+print("task 1: " + str(atleast100))