Day 18 Python solutions

Author: creideiki

18-1.py

@@ -0,0 +1,112 @@
+#!/usr/bin/env python
+
+from math import ceil, floor
+
+class Snailfish:
+    def __init__(self, pair):
+        if isinstance(pair, str):
+            pair = eval(pair)
+        self.pair = pair
+
+    def __add__(self, other):
+        p = Snailfish([self.pair, other.pair])
+        return p.reduce()
+
+    def reduce(self):
+        while True:
+            did_explode, new_pair = self.explode(self.pair)
+            self.pair = new_pair
+            if did_explode:
+                continue
+
+            did_split, new_pair = self.split(self.pair)
+            self.pair = new_pair
+            if did_split:
+                continue
+
+            break
+        return self
+
+    def increase_rightmost(self, element, increase):
+        if isinstance(element, int):
+            return element + increase
+
+        return [element[0], self.increase_rightmost(element[1], increase)]
+
+    def increase_leftmost(self, element, increase):
+        if isinstance(element, int):
+            return element + increase
+
+        return [self.increase_leftmost(element[0], increase), element[1]]
+
+    def inner_explode(self, element, level):
+        if level == 5 and isinstance(element, list):
+            return (True, 0, element[0], element[1])
+        elif isinstance(element, int):
+            return (False, element, None, None)
+        else:
+            new_right = element[1]
+
+            did_explode_left, new_left, propagate_left, propagate_right = self.inner_explode(element[0], level + 1)
+
+            if did_explode_left and propagate_right is not None and propagate_right > 0:
+                new_right = self.increase_leftmost(element[1], propagate_right)
+                propagate_right = 0
+
+            did_explode_right = False
+            if not did_explode_left:
+                did_explode_right, new_right, propagate_left, propagate_right = self.inner_explode(element[1], level + 1)
+
+            if did_explode_right and propagate_left is not None and propagate_left > 0:
+                new_left = self.increase_rightmost(element[0], propagate_left)
+                propagate_left = 0
+
+            return (
+                did_explode_left or did_explode_right,
+                [new_left, new_right],
+                propagate_left,
+                propagate_right
+            )
+
+    def explode(self, pair):
+        did_explode, new_pair, _, _ = self.inner_explode(pair, 1)
+        return (did_explode, new_pair)
+
+    def split(self, element):
+        if isinstance(element, int) and element >= 10:
+            return (True, [floor(element / 2), ceil(element / 2)])
+        elif isinstance(element, int):
+            return (False, element)
+        else:
+            did_split_left, new_left = self.split(element[0])
+            did_split_right = False
+            new_right = element[1]
+            if not did_split_left:
+                did_split_right, new_right = self.split(element[1])
+
+            return (
+                did_split_left or did_split_right,
+                [new_left, new_right]
+            )
+
+    def magnitude(self, element):
+        if isinstance(element, int):
+            return element
+        else:
+            return 3 * self.magnitude(element[0]) + 2 * self.magnitude(element[1])
+
+    def score(self):
+        return self.magnitude(self.pair)
+
+    def __str__(self):
+        return f"<{self.__class__.__name__}: {self.pair}>"
+
+
+numbers = [Snailfish(line.strip()) for line in open('18.input').readlines()]
+
+collect = numbers[0]
+
+for number in numbers[1:]:
+    collect += number
+
+print(collect.score())

18-2.py

@@ -0,0 +1,109 @@
+#!/usr/bin/env python
+
+from itertools import product
+from math import ceil, floor
+
+class Snailfish:
+    def __init__(self, pair):
+        if isinstance(pair, str):
+            pair = eval(pair)
+        self.pair = pair
+
+    def __add__(self, other):
+        p = Snailfish([self.pair, other.pair])
+        return p.reduce()
+
+    def reduce(self):
+        while True:
+            did_explode, new_pair = self.explode(self.pair)
+            self.pair = new_pair
+            if did_explode:
+                continue
+
+            did_split, new_pair = self.split(self.pair)
+            self.pair = new_pair
+            if did_split:
+                continue
+
+            break
+        return self
+
+    def increase_rightmost(self, element, increase):
+        if isinstance(element, int):
+            return element + increase
+
+        return [element[0], self.increase_rightmost(element[1], increase)]
+
+    def increase_leftmost(self, element, increase):
+        if isinstance(element, int):
+            return element + increase
+
+        return [self.increase_leftmost(element[0], increase), element[1]]
+
+    def inner_explode(self, element, level):
+        if level == 5 and isinstance(element, list):
+            return (True, 0, element[0], element[1])
+        elif isinstance(element, int):
+            return (False, element, None, None)
+        else:
+            new_right = element[1]
+
+            did_explode_left, new_left, propagate_left, propagate_right = self.inner_explode(element[0], level + 1)
+
+            if did_explode_left and propagate_right is not None and propagate_right > 0:
+                new_right = self.increase_leftmost(element[1], propagate_right)
+                propagate_right = 0
+
+            did_explode_right = False
+            if not did_explode_left:
+                did_explode_right, new_right, propagate_left, propagate_right = self.inner_explode(element[1], level + 1)
+
+            if did_explode_right and propagate_left is not None and propagate_left > 0:
+                new_left = self.increase_rightmost(element[0], propagate_left)
+                propagate_left = 0
+
+            return (
+                did_explode_left or did_explode_right,
+                [new_left, new_right],
+                propagate_left,
+                propagate_right
+            )
+
+    def explode(self, pair):
+        did_explode, new_pair, _, _ = self.inner_explode(pair, 1)
+        return (did_explode, new_pair)
+
+    def split(self, element):
+        if isinstance(element, int) and element >= 10:
+            return (True, [floor(element / 2), ceil(element / 2)])
+        elif isinstance(element, int):
+            return (False, element)
+        else:
+            did_split_left, new_left = self.split(element[0])
+            did_split_right = False
+            new_right = element[1]
+            if not did_split_left:
+                did_split_right, new_right = self.split(element[1])
+
+            return (
+                did_split_left or did_split_right,
+                [new_left, new_right]
+            )
+
+    def magnitude(self, element):
+        if isinstance(element, int):
+            return element
+        else:
+            return 3 * self.magnitude(element[0]) + 2 * self.magnitude(element[1])
+
+    def score(self):
+        return self.magnitude(self.pair)
+
+    def __str__(self):
+        return f"<{self.__class__.__name__}: {self.pair}>"
+
+
+lines = [line.strip() for line in open('18.input').readlines()]
+additions = [a for a in list(product(lines, lines)) if a[0] != a[1]]
+sums = [(Snailfish(a) + Snailfish(b)).score() for a, b in additions]
+print(max(sums))