From e6ab51fdd560d4320bcfd013a4cd016409303f78 Mon Sep 17 00:00:00 2001
From: Luke Hubmayer-Werner <mongoose41@gmail.com>
Date: Mon, 14 Dec 2020 19:30:01 +1030
Subject: [PATCH] 2020 Day 14 meme edition

---
 2020/day14_meme.py | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 2020/day14_meme.py

diff --git a/2020/day14_meme.py b/2020/day14_meme.py
new file mode 100644
index 0000000..3730520
--- /dev/null
+++ b/2020/day14_meme.py
@@ -0,0 +1,41 @@
+with open('input14', 'r') as file:
+  lines = [l.strip() for l in file.readlines()]
+
+def masks(m):
+  m_reset = int(m.replace('X', '1'), 2)
+  m_set = int(m.replace('X', '0'), 2)
+  return m_reset, m_set
+
+mem = {}
+m_reset = 0xFFFFFFFFFFFFFFFF
+m_set = 0
+for line in lines:
+    tokens = line.split()
+    if tokens[0] == 'mask':
+        m_reset, m_set = masks(tokens[-1])
+    elif tokens[0][:3] == 'mem':
+        mem[int(tokens[0][4:-1])] = int(tokens[-1]) & m_reset | m_set
+print(f'Part 1: {sum(mem.values())}')
+
+
+def mem_masks(m):
+  return m_set, fork_str
+
+mem = {}
+fork_str = ''
+xs = 0
+m_set = 0
+for line in lines:
+  tokens = line.split()
+  if tokens[0] == 'mask':
+    fork_str = tokens[-1]  #.replace('X', '{}')
+    xs = fork_str.count('X')
+    m_set = int(tokens[-1].replace('X', '0'), 2)
+  elif tokens[0][:3] == 'mem':
+    val = int(tokens[-1])
+    addr = f'{int(tokens[0][4:-1]) | m_set:036b}'
+    addr = ''.join(['{}' if f=='X' else c for c,f in zip(addr, fork_str)])
+    addrs = [addr.format(*f'{i:0{xs}b}') for i in range(2**xs)]
+    for a in addrs:
+      mem[a] = val
+print(f'Part 2: {sum(mem.values())}')