Solve day 10

2024/10_trails.py

@@ -0,0 +1,26 @@
+#!/usr/bin/env python3
+import sys
+from collections import Counter
+
+def trail_ends(grid, headx, heady):
+    h = len(grid)
+    w = len(grid[0])
+    work = [(headx, heady, 0, set())]
+    while work:
+        x, y, num, visited = work.pop()
+        if num == 9:
+            yield x, y
+        else:
+            for nb in ((x - 1, y), (x + 1, y), (x, y - 1), (x, y + 1)):
+                nx, ny = nb
+                if 0 <= nx < w and 0 <= ny < h and grid[ny][nx] == num + 1 \
+                        and nb not in visited:
+                    work.append((nx, ny, num + 1, visited | {nb}))
+
+grid = [list(map(int, line[:-1])) for line in sys.stdin]
+trails = [Counter(trail_ends(grid, x, y))
+          for y, row in enumerate(grid)
+          for x, num in enumerate(row)
+          if num == 0]
+print(sum(map(len, trails)))
+print(sum(sum(t.values()) for t in trails))

2024/input/10

@@ -0,0 +1,60 @@
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