Add day 21, 2024

Author: snhansen

2024/day21/solution.py

@@ -0,0 +1,135 @@
+import networkx as nx
+from itertools import product
+from functools import cache
+
+codes = """286A
+480A
+140A
+413A
+964A""".split("\n")
+
+kp_num = nx.grid_2d_graph(3, 4)
+kp_num.remove_node((0, 0))
+
+mapping = {
+    (0, 1): "1",
+    (0, 2): "4",
+    (0, 3): "7",
+    (1, 0): "0",
+    (1, 1): "2",
+    (1, 2): "5",
+    (1, 3): "8",
+    (2, 0): "A",
+    (2, 1): "3",
+    (2, 2): "6",
+    (2, 3): "9"
+}
+
+kp_num = nx.relabel_nodes(kp_num, mapping)
+
+kp_num_moves = {
+    ("A", "0"): "<",
+    ("0", "A"): ">",
+    ("A", "3"): "^",
+    ("3", "A"): "v",
+    ("0", "2"): "^",
+    ("2", "0"): "v",
+    ("3", "2"): "<",
+    ("2", "3"): ">",
+    ("3", "6"): "^",
+    ("6", "3"): "v",
+    ("2", "1"): "<",
+    ("1", "2"): ">",
+    ("2", "5"): "^",
+    ("5", "2"): "v",
+    ("1", "4"): "^",
+    ("4", "1"): "v",
+    ("6", "5"): "<",
+    ("5", "6"): ">",
+    ("6", "9"): "^",
+    ("9", "6"): "v",
+    ("5", "4"): "<",
+    ("4", "5"): ">",
+    ("5", "8"): "^",
+    ("8", "5"): "v",
+    ("4", "7"): "^",
+    ("7", "4"): "v",
+    ("9", "8"): "<",
+    ("8", "9"): ">",
+    ("8", "7"): "<",
+    ("7", "8"): ">"
+}
+
+kp_dir = nx.grid_2d_graph(3, 2)
+kp_dir.remove_node((0, 1))
+
+mapping = {
+    (0, 0): "<",
+    (1, 0): "v",
+    (2, 0): ">",
+    (1, 1): "^",
+    (2, 1): "A"
+}
+
+kp_dir = nx.relabel_nodes(kp_dir, mapping)
+
+kp_dir_moves = {
+    (">", "v"): "<",
+    ("v", ">"): ">",
+    (">", "A"): "^",
+    ("A", ">"): "v",
+    ("v", "<"): "<",
+    ("<", "v"): ">",
+    ("v", "^"): "^",
+    ("^", "v"): "v",
+    ("A", "^"): "<",
+    ("^", "A"): ">"
+}
+
+
+def get_num_inputs(output):
+    inputs = []
+    for x, y in zip("A" + output, output):
+        sub_inputs = []
+        paths = nx.all_shortest_paths(kp_num, x, y)
+        for path in paths:
+            sub_inputs.append("".join(kp_num_moves[(u, v)] for u, v in zip(path, path[1:])) + "A")
+        inputs.append(sub_inputs)
+
+    return [''.join(s) for s in product(*inputs)]
+
+
+def get_dir_inputs(output):
+    inputs = []
+    for x, y in zip("A" + output, output):
+        sub_inputs = []
+        paths = nx.all_shortest_paths(kp_dir, x, y)
+        for path in paths:
+            sub_inputs.append("".join(kp_dir_moves[(u, v)] for u, v in zip(path, path[1:])) + "A")
+        inputs.append(sub_inputs)
+    return [''.join(s) for s in product(*inputs)]
+
+
+@cache
+def min_length(buttons, n):
+    if  n == 0:
+        return len(buttons)
+    assert buttons[-1] == "A"
+    if buttons.count("A") > 1:
+        ls = [x + "A" for x in buttons.split("A")][:-1]
+        return sum(min_length(pt, n) for pt in ls)
+    else:
+        return min(min_length(x, n - 1) for x in get_dir_inputs(buttons))
+
+
+def complexity(code, n):
+    seqs = get_num_inputs(code)
+    min_len = min(min_length(seq, n) for seq in seqs)
+    return min_len*int(code[:-1])
+
+
+# Part 1
+print(sum(complexity(code, 2) for code in codes))
+
+# Part 2
+print(sum(complexity(code, 25) for code in codes))