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adventofcode/2024/06/part2.py

29 lines
866 B
Python

from part1 import *
thoughts = \
"""
So, we can place an obstacle on each of the 130*130 - #obstacles = 16900
- obstacles positions, but the initial path only covers 1512 positions
(thus 1512 - 1 = 1511 steps). By instead placing an obstacle on each of
those steps, we can find a loop.
The other thing we need to do, is detect loops. For that, It would be
nice to store both positions and directions to establish uniqueness,
or just check whether it is the fifth time in a position (as we have
then travelled to that position at least twice from at least one
position; see Pigeonhole principle).
"""
if __name__ == "__main__":
m = Map()
#m.load_map("testinput")
m.load_map("input")
while m.step():
# After each step, we can fork the map and add the obstacle.
print(m.pos, m.direction)
#m.show()
print(len(m.trace), m.trace)
print(len(set(m.trace)))