From 7bf24fbbdb625de98ac2ff4dc5fd068b8f732d71 Mon Sep 17 00:00:00 2001
From: Alex Karle <alex@alexkarle.com>
Date: Fri, 13 Dec 2024 02:52:07 +0100
Subject: [PATCH] 2024: Add day 12

---
 2024/12/1.py | 44 ++++++++++++++++++++++++++++++++++++++++++++
 2024/12/2.py | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 95 insertions(+)
 create mode 100755 2024/12/1.py
 create mode 100755 2024/12/2.py

diff --git a/2024/12/1.py b/2024/12/1.py
new file mode 100755
index 0000000..56692d4
--- /dev/null
+++ b/2024/12/1.py
@@ -0,0 +1,44 @@
+#!/usr/bin/env python3
+import sys
+
+def parse():
+    G = []
+    for l in sys.stdin:
+        G.append([c for c in l.strip()])
+    return G
+
+def cost(G):
+    def get(i, j):
+        if i < 0 or j < 0 or i >= len(G) or j >= len(G[0]):
+            return None
+        return G[i][j]
+
+    stk = []
+    seen = set()
+    tot = 0
+    for i0 in range(len(G)):
+        for j0 in range(len(G[0])):
+            if (i0, j0) not in seen:
+                stk.append((i0, j0))
+            # explore the plot
+            a = 0
+            p = 0
+            while stk:
+                (i, j) = stk.pop()
+                seen.add((i, j))
+                crop = G[i][j]
+                a += 1
+                for n in [(i+1,j),(i-1,j),(i,j+1),(i,j-1)]:
+                    if get(n[0],n[1]) == crop:
+                        if n not in seen:
+                            seen.add(n)
+                            stk.append(n)
+                    else:
+                        p += 1
+                # print((crop, i, j, a, p))
+            tot += a*p
+    return tot
+
+if __name__ == '__main__':
+    G = parse()
+    print(cost(G))
diff --git a/2024/12/2.py b/2024/12/2.py
new file mode 100755
index 0000000..2eab9a2
--- /dev/null
+++ b/2024/12/2.py
@@ -0,0 +1,51 @@
+#!/usr/bin/env python3
+import sys
+
+def parse():
+    G = []
+    for l in sys.stdin:
+        G.append([c for c in l.strip()])
+    return G
+
+def cost(G):
+    def get(i, j):
+        if i < 0 or j < 0 or i >= len(G) or j >= len(G[0]):
+            return None
+        return G[i][j]
+
+    stk = []
+    seen = set()
+    tot = 0
+    for i0 in range(len(G)):
+        for j0 in range(len(G[0])):
+            if (i0, j0) not in seen:
+                stk.append((i0, j0))
+            # explore the plot
+            a = 0
+            p = 0
+            while stk:
+                (i, j) = stk.pop()
+                seen.add((i, j))
+                crop = G[i][j]
+                a += 1
+                for n in [(i+1,j),(i-1,j),(i,j+1),(i,j-1)]:
+                    if get(n[0],n[1]) == crop:
+                        if n not in seen:
+                            seen.add(n)
+                            stk.append(n)
+                # unlike counting the perimeter, we count the
+                # _corners_ which is equivalent to the number of sides
+                for dy, dx in [(-1,-1),(-1,1),(1,-1),(1,1)]:
+                    # outside corner is when both adjacent neighbors are diff
+                    if get(i+dy,j) != crop and get(i,j+dx) != crop:
+                        p += 1
+                    # inside corner is when both adjacent neighbors are same but diag diff
+                    elif get(i+dy,j) == crop and get(i,j+dx) == crop and get(i+dy,j+dx) != crop:
+                        p += 1
+                # print((crop, i, j, a, p))
+            tot += a*p
+    return tot
+
+if __name__ == '__main__':
+    G = parse()
+    print(cost(G))
--
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