[2024/12] p2 solved

2024/12/example_ab

@@ -0,0 +1,6 @@
+AAAAAA
+AAABBA
+AAABBA
+ABBAAA
+ABBAAA
+AAAAAA

2024/12/example_ex

@@ -0,0 +1,5 @@
+EEEEE
+EXXXX
+EEEEE
+EXXXX
+EEEEE

2024/12/example_xo

@@ -0,0 +1,5 @@
+OOOOO
+OXOXO
+OOOOO
+OXOXO
+OOOOO

2024/12/script.py

@@ -1,6 +1,7 @@
 from GhostyUtils import aoc
 from GhostyUtils.grid import Grid
 from GhostyUtils.vec2 import Vec2, Dir
+from collections import defaultdict
 
 
 def area(region: list[Vec2]) -> int:
@@ -10,19 +11,44 @@ def area(region: list[Vec2]) -> int:
 def neighbours(pos: Vec2) -> list[Vec2]:
     return [
         (pos + Vec2(Dir.UP)).as_tuple(),
-        (pos + Vec2(Dir.RIGHT)).as_tuple(),
         (pos + Vec2(Dir.DOWN)).as_tuple(),
         (pos + Vec2(Dir.LEFT)).as_tuple(),
+        (pos + Vec2(Dir.RIGHT)).as_tuple(),
     ]
 
 
-def perimeter(region: list[Vec2]) -> int:
+def perimeter(region: set[tuple]) -> int:
     p = 0
     for pos in region:
-        p += sum(1 for n in neighbours(pos) if n not in region)
+        p += sum(n not in region for n in neighbours(pos))
     return p
 
 
+def sides(region: set[tuple]) -> int:
+    fences = defaultdict(list)
+    for pos in region:
+        for n, d in Dir.map_nswe(neighbours(pos)).items():
+            if n not in region:
+                fences[d].append(pos)
+    for d, fs in fences.items():
+        fences[d] = sorted(fs, key=lambda f: f[::-1] if d in {Dir.N, Dir.S} else f)
+
+    num_sides = 0
+    dirmap = {
+        Dir.N: Dir.E,
+        Dir.S: Dir.E,
+        Dir.W: Dir.S,
+        Dir.E: Dir.S,
+    }
+    for d, fs in fences.items():
+        num_sides += 1
+        for f1, f2 in zip(fs, fs[1:]):
+            if (Vec2(f1) + dirmap[d]).as_tuple() != f2:
+                num_sides += 1
+
+    return num_sides
+
+
 def main():
     grid = Grid(aoc.read_lines())
     regions = []
@@ -37,13 +63,18 @@ def main():
     if aoc.args.progress or aoc.args.verbose:
         for region in regions:
             r = grid[next(iter(region))]
-            print(f"{r} | area: {area(region)}, perimeter: {perimeter(region)}, "
-                  f"cost: {area(region) * perimeter(region)}")
+            print(f"{r} | "
+                  f"area: {area(region)}, "
+                  f"perimeter: {perimeter(region)}, "
+                  f"sides: {sides(region)} | "
+                  f"p1 cost: {area(region) * perimeter(region)} | "
+                  f"p2 cost: {area(region) * sides(region)}")
             if aoc.args.verbose:
                 print(f"> {region}")
         print(f"{len(regions)} regions")
 
     print(f"p1: {sum(area(region) * perimeter(region) for region in regions)}")
+    print(f"p2: {sum(area(region) * sides(region) for region in regions)}")
 
 
 if __name__ == "__main__":

README.md

@@ -3,10 +3,10 @@ My solutions to the yearly Advents of Code
 
 <!-- AOC TILES BEGIN -->
 <h1 align="center">
-  Advent of Code - 184/474 ⭐
+  Advent of Code - 185/476 ⭐
 </h1>
 <h1 align="center">
-  2024 - 23 ⭐ - Python
+  2024 - 24 ⭐ - Python
 </h1>
 <a href="2024/1/script.py">
   <img src=".aoc_tiles/tiles/2024/01.png" width="161px">