38 lines
1013 B
Python
38 lines
1013 B
Python
with open("day4/input.txt") as file:
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paperrolls = [list(line.strip("\n")) for line in file.readlines()]
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h = len(paperrolls)
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w = len(paperrolls[0]) if h>0 else 0
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dirs = [(-1,-1),(-1,0),(-1,1),(0,-1),(0,1),(1,-1),(1,0),(1,1)]
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def neighbor_count(g, r, c):
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cnt = 0
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for dr, dc in dirs:
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rr, cc = r+dr, c+dc
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if 0 <= rr < h and 0 <= cc < w and g[rr][cc] == '@':
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cnt += 1
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return cnt
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# total rolls
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total = sum(row.count('@') for row in paperrolls)
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# compute 4-core complement by iterative simultaneous removal
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g = [row[:] for row in paperrolls]
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removed = 0
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while True:
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to_remove = []
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for r in range(h):
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for c in range(w):
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if g[r][c] == '@' and neighbor_count(g, r, c) < 4:
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to_remove.append((r,c))
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if not to_remove:
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break
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removed += len(to_remove)
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for r,c in to_remove:
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g[r][c] = '.'
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print("Total rolls:", total)
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print("Removable (eventually):", removed)
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print("Remaining in 4-core:", total - removed) |