chore: create new project structure and aoc.py runner script

adventofcode/2023/day8/day8.py

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+import re
+import math
+from itertools import cycle
+
+def parse_input(infile):
+    with open(infile) as f:
+        content = f.read().rstrip()
+        directions, nodes = content.split("\n\n")
+        directions = directions.strip()
+        nodes = nodes.split("\n")
+        nodes = [n.split(" = ") for n in nodes]
+        nodes = {k: re.findall(r"\w{3}", v) for k, v in nodes}
+        return directions, nodes
+
+
+def part1(directions, nodes):
+    iterations = 0
+    current_node = "AAA"
+    for d in cycle(directions):
+        if current_node == "ZZZ":
+            break
+        iterations += 1
+        if d == "L":
+            current_node = nodes[current_node][0]
+        else:
+            current_node = nodes[current_node][1]
+    print(f"Part 1: reached 'ZZZ' in {iterations} iterations")
+
+
+def part2(directions, nodes):
+    current_nodes = [k for k in nodes.keys() if k.endswith("A")]
+    # keep track of iterations number for each visited node 
+    # (the number will stop to beeing incremented once the node n_i value reached the target value 'xxZ')
+    iterations = [0] * len(current_nodes)
+
+    for d in cycle(directions):
+        if all(c.endswith("Z") for c in current_nodes):
+            break
+
+        if d == "L":
+            new_nodes = []
+            for i, n in enumerate(current_nodes):
+                if n.endswith("Z"):  # end condition already reached for this node
+                    new_nodes.append(n)
+                else:
+                    new_nodes.append(nodes[n][0])
+                    iterations[i] += 1
+            current_nodes = new_nodes
+        else:
+            new_nodes = []
+            for i, n in enumerate(current_nodes):
+                if n.endswith("Z"):  # end condition already reached for this node
+                    new_nodes.append(n)
+                else:
+                    new_nodes.append(nodes[n][1])
+                    iterations[i] += 1
+            current_nodes = new_nodes
+
+    # the result is the lowest common multiple between the number of iterations
+    # for each node
+    result = math.lcm(*iterations)
+    print(f"Part 2: reached all nodes such that 'xxZ' in {result} iterations")
+
+
+if __name__ == "__main__":
+    import sys
+    import os
+    SCRIPTPATH = os.path.dirname(os.path.realpath(__file__))
+    infile = sys.argv[1] if len(sys.argv) == 2 else "example.txt"
+
+    directions, nodes = parse_input(os.path.join(SCRIPTPATH, infile))
+    part1(directions, nodes)
+
+    directions, nodes = parse_input(os.path.join(SCRIPTPATH, infile))
+    part2(directions, nodes)