Add solution for tests that runs too slow

year_2023/day08/haunted_wasteland.py

@@ -7,6 +7,9 @@
 END = "ZZZ"
 START = "AAA"
 
+END_CHAR = "Z"
+START_CHAR = "A"
+
 
 def get_num_steps(puzzle_input):
     lines = puzzle_input.split("\n")
@@ -28,7 +31,22 @@ def get_num_steps(puzzle_input):
 
 
 def get_num_steps_ghost(puzzle_input):
-    return 0
+    lines = puzzle_input.split("\n")
+    instructions = lines[0]
+    node_inputs = lines[2:]
+    nodes = {}
+    for ni in node_inputs:
+        node, connections = ni.split(" = ")
+        left, right = connections[1:-1].split(", ")
+        nodes[node] = {LEFT: left, RIGHT: right}
+
+    current_nodes = [n for n in nodes if n.endswith(START_CHAR)]
+    num_steps = 0
+    while any(not n.endswith(END_CHAR) for n in current_nodes):
+        next_instruction = instructions[num_steps % len(instructions)]
+        current_nodes = [nodes[n][next_instruction] for n in current_nodes]
+        num_steps += 1
+    return num_steps
 
 
 if __name__ == "__main__":