From f4d8aef7021936c2e2460457fd717f3323f01ff8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=B8ren=20Rasmussen?= <sr@jondahl.net>
Date: Mon, 1 Feb 2021 08:38:55 +0100
Subject: [PATCH] Add day 11, kgn solution

---
 2020/11/kgn.py | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)
 create mode 100644 2020/11/kgn.py

diff --git a/2020/11/kgn.py b/2020/11/kgn.py
new file mode 100644
index 0000000..5e2fb39
--- /dev/null
+++ b/2020/11/kgn.py
@@ -0,0 +1,64 @@
+import copy
+
+
+def mutate(seats, seatscopy, row, col, nocc, visible):
+    changed = False
+    if seats[row][col] == 'L':
+        if nocc == 0:
+            seatscopy[row][col] = '#'
+            changed = True
+    elif seats[row][col] == '#':
+        if nocc >= visible:
+            seatscopy[row][col] = 'L'
+            changed = True
+
+    return changed
+
+
+def occ(seats, numseats, seatlen, row, col, visible):
+    nocc = 0
+    for dr in [-1, 0, 1]:
+        for dc in [-1, 0, 1]:
+            if not (dr == 0 and dc == 0):
+                rr = row + dr
+                cc = col + dc
+
+                if visible > 4:
+                    while 0 <= rr < numseats and 0 <= cc < seatlen and seats[rr][cc] == '.':
+                        rr = rr + dr
+                        cc = cc + dc
+
+                if 0 <= rr < numseats:
+                    if 0 <= cc < seatlen:
+                        if seats[rr][cc] == '#':
+                            nocc += 1
+    return nocc
+
+
+def solve(seats, visible):
+    numseats = len(seats)
+    seatlen = len(seats[0])
+    while True:
+        seatscopy = copy.deepcopy(seats)
+        changed = False
+        for row in range(numseats):
+            for col in range(seatlen):
+                nocc = occ(seats, numseats, seatlen, row, col, visible)
+                changed |= mutate(seats, seatscopy, row, col, nocc, visible)
+
+        if not changed:
+            break
+        seats = copy.deepcopy(seatscopy)
+
+    result = 0
+    for row in range(numseats):
+        for col in range(seatlen):
+            if seats[row][col] == '#':
+                result += 1
+    return result
+
+
+with open('data.txt', 'r') as f:
+    seats = [list(x.strip()) for x in f.readlines()]
+    print(solve(seats, 4))
+    print(solve(seats, 5))