2025(08): solve part 1 (it's not quick)

CPU times: user 3.14 s, sys: 0 ns, total: 3.14 s
Wall time: 3.15 s

2025/08/README.md

@@ -57,3 +57,11 @@ This process continues for a while, and the Elves are concerned that they don't
 After making the ten shortest connections, there are 11 circuits: one circuit which contains _5_ junction boxes, one circuit which contains _4_ junction boxes, two circuits which contain _2_ junction boxes each, and seven circuits which each contain a single junction box. Multiplying together the sizes of the three largest circuits (5, 4, and one of the circuits of size 2) produces _`40`_.
 
 Your list contains many junction boxes; connect together the _1000_ pairs of junction boxes which are closest together. Afterward, _what do you get if you multiply together the sizes of the three largest circuits?_
+
+### Part Two
+
+The Elves were right; they _definitely_ don't have enough extension cables. You'll need to keep connecting junction boxes together until they're all in _one large circuit_.
+
+Continuing the above example, the first connection which causes all of the junction boxes to form a single circuit is between the junction boxes at `216,146,977` and `117,168,530`. The Elves need to know how far those junction boxes are from the wall so they can pick the right extension cable; multiplying the X coordinates of those two junction boxes (`216` and `117`) produces _`25272`_.
+
+Continue connecting the closest unconnected pairs of junction boxes together until they're <span title="I strongly recommend making an interactive visualizer for this one; it reminds me a lot of maps from futuristic space games.">all in the same circuit</span>. _What do you get if you multiply together the X coordinates of the last two junction boxes you need to connect?_

2025/08/part1.py

@@ -1,4 +1,5 @@
 import numpy as np
+from math import prod
 
 
 debug = False
@@ -61,6 +62,7 @@ def get_circuits(junctions, connections):
 	"""
 	# circuits = [[x] for x in range(len(junctions))]
 	circuits = [list(x) for x in connections]
+	circuits += [[x] for x in range(len(junctions))]
 	changed = True
 	while changed:
 		changed = False
@@ -69,19 +71,27 @@ def get_circuits(junctions, connections):
 				for x in circuits[i]:
 					if x in circuits[j]:
 						# NOTE: Elements might appear multiple times per circuit.
-						circuits[i] += circuits.pop[j]
+						circuits[i] += circuits[j]
+						circuits[j] = []
 						changed = True
 	return circuits
 
+def product_largest_three_circuits(junctions, num_of_connections):
+	X, Y, dists = distances(junctions)
+	connections = []
+
+	for i in range(num_of_connections):
+		x, y = X[i], Y[i]
+		connections.append((x, y))
+
+	circuits = get_circuits(junctions, connections)
+	lengths = [len(set(circuit)) for circuit in circuits if circuit != []]
+	lengths.sort()
+	return prod(lengths[-3:])
 
 if __name__ == "__main__":
 	test_junctions = load_junctions("testinput")
-	X, Y, dists = distances(test_junctions)
-	connections = []
-	# unconnected = list(range(len(test_junctions)))
+	assert product_largest_three_circuits(test_junctions, 10) == 40
 
-	for i in range(len(X)):
-		x, y = X[i], Y[i]
-		if not is_connected(x, connections) and not is_connected(y, connections):
-			connections.append((x, y))
-	print(len(connections))
+	junctions = load_junctions("input")
+	print(product_largest_three_circuits(junctions, 1000))