[py] Solve 2022_09

py/aoc/y2022/d09.py

@@ -0,0 +1,25 @@
+def sign(n):
+    return 0 if n == 0 else n // abs(n)
+
+
+def simulate_rope(input, segments):
+    knots = [[0, 0] for _ in range(segments)]
+    trail = {(0, 0)}
+    for line in input.splitlines():
+        direction, amount = line.split()
+        hdx, hdy = {"L": (-1, 0), "R": (1, 0), "D": (0, -1), "U": (0, 1)}[direction]
+        for _ in range(int(amount)):
+            knots[0][0] += hdx
+            knots[0][1] += hdy
+            for i in range(1, len(knots)):
+                dx, dy = knots[i - 1][0] - knots[i][0], knots[i - 1][1] - knots[i][1]
+                if abs(dx) > 1 or abs(dy) > 1:
+                    knots[i][0] += sign(dx)
+                    knots[i][1] += sign(dy)
+            trail.add(tuple(knots[-1]))
+    return len(trail)
+
+
+def solve(inputstr):
+    print(f"Part 1: {simulate_rope(inputstr, 2)}")
+    print(f"Part 2: {simulate_rope(inputstr, 10)}")