X-Git-Url: https://git.friedersdorff.com/?a=blobdiff_plain;f=14_2.py;fp=14_2.py;h=0a5046b31f144e9025e4385df2501c475063d3dd;hb=5accd75b77aeb92f15e2a9fac235c88a8f7c86fe;hp=0000000000000000000000000000000000000000;hpb=51c5bd4e54ddb0a8a41255b58ff8ffa620db0b99;p=max%2Fadvent_of_code_2021.git

diff --git a/14_2.py b/14_2.py
new file mode 100644
index 0000000..0a5046b
--- /dev/null
+++ b/14_2.py
@@ -0,0 +1,37 @@
+""" Pair insertion """
+import pprint
+import collections
+
+insertion_rules = {}
+
+polymer_pairs = collections.defaultdict(int)
+
+letter_count = collections.defaultdict(int)
+
+with open("14_input.txt") as f:
+    polymer_template = f.readline().strip()
+    f.readline()
+
+    for line in f:
+        pair, insert = line.strip().split(" -> ")
+        insertion_rules[pair] = insert
+
+for i in range(len(polymer_template) - 1):
+    pair = str(polymer_template[i:i+2])
+    polymer_pairs[str(polymer_template[i:i+2])] += 1
+
+print(polymer_pairs)
+
+for _ in range(40):
+    new_polymer_pairs = collections.defaultdict(int)
+    for pair, n in polymer_pairs.items():
+        insert = insertion_rules[pair]
+
+        new_polymer_pairs[f"{pair[0]}{insert}"] += n
+        new_polymer_pairs[f"{insert}{pair[0]}"] += n
+        letter_count[insert] += n
+
+    polymer_pairs = new_polymer_pairs
+
+print(letter_count)
+print(max(letter_count.values()) - min(letter_count.values()))