2023 - Day 8 part 2

2023/8/8_2.py

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+#!/usr/bin/env python
+# 2023 - Advent Of Code 8 - part 2
+
+from math import lcm
+from functools import reduce
+
+#file = 'input_example2.txt'
+file = 'input.txt'
+
+
+# pylint: disable=consider-using-with
+input_lines = [line.strip('\n') for line in open(file, encoding="utf-8")]
+
+directions = input_lines[0]
+print(directions)
+
+nodes = {}
+for l in input_lines[2:]:
+    k, v = l.split(' = ')
+    nodes[k] = v[1:-1].split(', ')
+
+cur_nodes = [x for x in nodes if x.endswith('A')]
+print(cur_nodes)
+
+allz = False
+count = 0
+ends_num = [0] * len(cur_nodes)
+while not allz:
+    ends = [False] * len(cur_nodes)
+    for current, _ in enumerate(cur_nodes):
+        # print(cur_node)
+
+        if directions[count % len(directions)] == 'L':
+            cur_nodes[current] = nodes[cur_nodes[current]][0]
+        elif directions[count % len(directions)] == 'R':
+            cur_nodes[current] = nodes[cur_nodes[current]][1]
+        # check z
+        if cur_nodes[current].endswith('Z'):
+            ends[current] = True
+            ends_num[current] = count
+            print(f'end {cur_nodes[current]} found at {count} for {current} {ends}')
+    allz = False not in ends
+    if True in ends:
+        # print(f'end found at {count} {ends}')
+        print(f'ends list: {ends_num}')
+    if 0 not in ends_num:
+        break
+    count += 1
+
+print()
+print(f'count: {count} {ends}')
+print(f'{ends_num}')
+ends_num2 = [x + 1 for x in ends_num]
+print(f'reduced: {reduce(lcm, ends_num)}')
+print(f'reduced: {reduce(lcm, ends_num2)}')

2023/8/input_example2.txt

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+LR
+
+11A = (11B, XXX)
+11B = (XXX, 11Z)
+11Z = (11B, XXX)
+22A = (22B, XXX)
+22B = (22C, 22C)
+22C = (22Z, 22Z)
+22Z = (22B, 22B)
+XXX = (XXX, XXX)