AoC day 13 - big 🤖 assist for pt2

2024/day13/day13.py

@@ -0,0 +1,78 @@
+import sys, os,re
+sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'common'))
+from common import open_file, print_and_verify_answer
+
+def get_numbers_from_line(line):
+    pattern = r"X[+=](\d+), Y[+=](\d+)"
+    match = re.search(pattern, line)
+    return [int(match.group(1)), int(match.group(2))]
+
+def calculate_games(data_file, is_part_two = False):
+    games = []
+    for line in data_file:
+        if "Button A" in line:
+            this_game = []
+            x,y = get_numbers_from_line(line)
+            this_game.append([x, y])
+        elif "Button B" in line:
+            x,y = get_numbers_from_line(line)
+            this_game.append([x, y])
+        elif "Prize" in line:
+            x,y = get_numbers_from_line(line)
+            if is_part_two:
+                this_game.append([x+10000000000000, y+10000000000000])
+            else:
+                this_game.append([x, y])
+        elif line == "\n":
+            games.append(this_game)
+    games.append(this_game) # add the last game...
+    return games
+
+# Brute force solver courtesy of my own dumb brain
+def run_part_one(mode, expected = None):
+    data_file = open_file( mode + ".txt")
+    games = calculate_games(data_file)
+    total_tokens_used = 0
+    for input in games:
+        for x_multiplier in range(0,100):
+            for y_multiplier in range(0,100):
+                x = x_multiplier * input[0][0] + y_multiplier * input[1][0]
+                y = x_multiplier * input[0][1] + y_multiplier * input[1][1]
+                if x == input[2][0] and y == input[2][1]:
+                    total_tokens_used += (3 * x_multiplier) + y_multiplier
+                    break
+    print_and_verify_answer(mode, "one", total_tokens_used, expected)
+
+# Linear equation solver courtesy of GPT4o
+def run_part_two(mode, expected = None):
+    data_file = open_file( mode + ".txt")
+    games = calculate_games(data_file, True)
+    total_tokens_used = 0
+    for input in games:
+        x1, y1 = input[0]
+        x2, y2 = input[1]
+        x_target, y_target = input[2]
+
+        # Solve the system of linear equations:
+        # x = x_multiplier * x1 + y_multiplier * x2
+        # y = x_multiplier * y1 + y_multiplier * y2
+        # We need to find x_multiplier and y_multiplier such that x == x_target and y == y_target
+        det = x1 * y2 - x2 * y1
+        if det == 0:
+            continue  # No solution if determinant is zero
+
+        # Calculate the multipliers
+        x_multiplier = (x_target * y2 - x2 * y_target) // det
+        y_multiplier = (x1 * y_target - x_target * y1) // det
+        if (x_multiplier * x1 + y_multiplier * x2 == x_target and
+            x_multiplier * y1 + y_multiplier * y2 == y_target):
+            total_tokens_used += (3 * x_multiplier) + y_multiplier
+
+    print_and_verify_answer(mode, "two", total_tokens_used, expected)
+
+# ADD EXPECTED OUTPUTS TO TESTS HERE 👇
+run_part_one("test", 480)
+run_part_one("prod", 26810)
+run_part_two("test", 875318608908) # Implied, they don't say.
+run_part_two("prod", 108713182988244)
+# Now run it and watch the magic happen 🪄

2024/day13/test.txt

@@ -0,0 +1,15 @@
+Button A: X+94, Y+34
+Button B: X+22, Y+67
+Prize: X=8400, Y=5400
+
+Button A: X+26, Y+66
+Button B: X+67, Y+21
+Prize: X=12748, Y=12176
+
+Button A: X+17, Y+86
+Button B: X+84, Y+37
+Prize: X=7870, Y=6450
+
+Button A: X+69, Y+23
+Button B: X+27, Y+71
+Prize: X=18641, Y=10279

README.md

@@ -15,7 +15,7 @@ Started in 2022, but I'll backfill previous years when I need a festive boost.
 ⬜ = incomplete or not attempted  
 
 ### Stats
-**2024:**  🟧🟧🟧🟧🟧🟧🟧🟧🟧🟧🟧🟧⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜ _(24)_  
+**2024:**  🟧🟧🟧🟧🟧🟧🟧🟧🟧🟧🟧🟧🟧⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜ _(26)_  
 **2023:**  🟨🟨🟨🟨🟧🟨🟨🟧⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜ _(16)_  
 **2022:**  🟨🟨🟨🟨🟨🟨🟨🟨🟨🟨🟨🟧🟨🟨⬛⬜⬜⬛⬜⬛🟨⬜🟨⬜⬛ _(36)_  
 **2021:**  🟨🟨🟨🟨🟨🟨🟨🟨⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜ _(16)_