Solution to problem 8 in Python

src/Year_2017/P8.py

@@ -1,21 +1,92 @@
+# --- Day 8: I Heard You Like Registers ---
+
+# You receive a signal directly from the CPU. Because of your recent assistance
+# with jump instructions, it would like you to compute the result of a series
+# of unusual register instructions.
+
+# Each instruction consists of several parts: the register to modify, whether
+# to increase or decrease that register's value, the amount by which to
+# increase or decrease it, and a condition. If the condition fails, skip the
+# instruction without modifying the register. The registers all start at 0. The
+# instructions look like this:
+
+# b inc 5 if a > 1
+# a inc 1 if b < 5
+# c dec -10 if a >= 1
+# c inc -20 if c == 10
+
+# These instructions would be processed as follows:
+
+#     Because a starts at 0, it is not greater than 1, and so b is not
+# modified.
+#     a is increased by 1 (to 1) because b is less than 5 (it is 0).
+#     c is decreased by -10 (to 10) because a is now greater than or equal to 1
+# (it is 1).
+#     c is increased by -20 (to -10) because c is equal to 10.
+
+# After this process, the largest value in any register is 1.
+
+# You might also encounter <= (less than or equal to) or != (not equal to).
+# However, the CPU doesn't have the bandwidth to tell you what all the
+# registers are named, and leaves that to you to determine.
+
+# What is the largest value in any register after completing the instructions
+# in your puzzle input?
+
 from collections import defaultdict
+from typing import Dict
 
 with open("files/P8.txt") as f:
     instructions = [line for line in f.read().strip().split("\n")]
 
-# print(instructions)
 
-registry: dict[str, int] = defaultdict(int)
-
-
-def inc(s: str) -> None:
+def inc(s: str, dic: Dict[str, int]) -> None:
     reg, inst, num, iff, reg_cond, op, num_cond = s.split()
-    if eval("registry[reg_cond] " + op + num_cond):
-        registry[reg] += int(num)
+    if eval("dic[reg_cond] " + op + num_cond):
+        dic[reg] += int(num)
 
 
+def dec(s: str, dic: Dict[str, int]) -> None:
+    reg, inst, num, iff, reg_cond, op, num_cond = s.split()
+    if eval("dic[reg_cond] " + op + num_cond):
+        dic[reg] -= int(num)
+
+
+def part_1() -> None:
+    registry: Dict[str, int] = defaultdict(int)
     for instruction in instructions:
-    inc(instruction)
-    break
+        if "inc" in instruction:
+            inc(instruction, registry)
+        elif "dec" in instruction:
+            dec(instruction, registry)
 
-print(registry)
+    val = max(registry.values())
+
+    print(f"The largest value in the registry is {val}")
+
+
+# --- Part Two ---
+
+# To be safe, the CPU also needs to know the highest value held in any register
+# during this process so that it can decide how much memory to allocate to
+# these operations. For example, in the above instructions, the highest value
+# ever held was 10 (in register c after the third instruction was evaluated).
+
+
+def part_2() -> None:
+    registry: Dict[str, int] = defaultdict(int)
+    max_val = 0
+    for instruction in instructions:
+        if "inc" in instruction:
+            inc(instruction, registry)
+        elif "dec" in instruction:
+            dec(instruction, registry)
+
+        max_val = max(max_val, max(registry.values()))
+
+    print(f"The largest value ever held by the registry is {max_val}")
+
+
+if __name__ == "__main__":
+    part_1()
+    part_2()