2024-20 python p1

1 files changed, 39 insertions, 0 deletions

diff --git a/2024/20/python/main.py b/2024/20/python/main.py
new file mode 100644
index 0000000..c2f3f73
--- /dev/null
+++ b/2024/20/python/main.py
@@ -0,0 +1,39 @@
+from fileinput import input
+
+grid = {
+    complex(idx, idy): c
+    for idy, line in enumerate(input())
+    for idx, c in enumerate(line.strip())
+}
+start = next(p for p, c in grid.items() if c == "S")
+end = next(p for p, c in grid.items() if c == "E")
+
+times = {}
+q = [(start, 0)]
+while q:
+    curr, t = q.pop()
+    if curr in times:
+        continue
+    times[curr] = t
+    for d in [1, -1, 1j, -1j]:
+        x = curr + d
+        if x not in grid or grid[x] == "#":
+            continue
+        q.append((x, t + 1))
+
+cheats = []
+for wall in (p for p, c in grid.items() if c == "#"):
+    for d in [1, -1, 1j, -1j]:
+        if (x := wall - d) not in grid or grid[x] == "#":
+            continue
+        if (y := wall + d) not in grid or grid[y] == "#":
+            continue
+        if (saved := times[y] - times[x] - 2) <= 0:
+            continue
+        cheats.append(saved)
+
+silver = sum(1 for c in cheats if c >= 100)
+gold = 0
+
+print("silver:", silver)
+print("gold:", gold)