Add day 14 - phew

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

day14/day14.py

@@ -0,0 +1,68 @@
+#!/usr/bin/env python3
+import sys
+from collections import defaultdict, Counter
+from typing import DefaultDict, Mapping
+from copy import deepcopy
+
+
+def apply_rules(template: str, rules: Mapping[str, str]) -> str:
+    # sliding window babey
+    new = ""
+    for i in range(len(template) - 1):
+        new += template[i] + rules[template[i : i + 2]]
+    return new + template[-1]
+
+
+def part1(template: str, rules: Mapping[str, str]):
+    for i in range(10):
+        template = apply_rules(template, rules)
+    counts: DefaultDict[str, int] = defaultdict(lambda: 0)
+    for c in template:
+        counts[c] += 1
+    counts_sorted = sorted(counts.items(), key=lambda pair: pair[1])
+    _, least = counts_sorted[0]
+    _, most = counts_sorted[-1]
+    print(most - least)
+
+
+def part2(template: str, rules: Mapping[str, str]):
+    # Apply rules with counts instead of building a string
+    counts: Counter = Counter()
+
+    for i in range(len(template) - 1):
+        counts[template[i : i + 2]] += 1
+
+    for _ in range(40):
+        new_counts: Counter = Counter()
+        for pair, count in counts.items():
+            # Create the two new pairs, and remove the old one
+            rule = rules[pair]
+            p1 = pair[0] + rule
+            p2 = rule + pair[1]
+            # Subtract from this pair, and then add the new ones
+            new_counts[p1] += counts[pair]
+            new_counts[p2] += counts[pair]
+        counts = new_counts
+    # Count all the letters, only using the first character.
+    # If we count the second character, we double-count.
+    letters: Counter = Counter()
+    for pair in counts:
+        letters[pair[0]] += counts[pair]
+    # We just need to count the last character in the original template - since this never changes.
+    letters[template[-1]] += 1
+    print(max(letters.values()) - min(letters.values()))
+
+
+template = sys.stdin.readline().strip()
+# blank
+sys.stdin.readline()
+rules = {
+    rule: translate.strip()
+    for rule, translate in map(lambda line: line.split(" -> "), sys.stdin)
+}
+
+
+print("Part 1")
+part1(template, rules)
+print("Part 2")
+part2(template, rules)