125 lines
No EOL
2.8 KiB
Python
125 lines
No EOL
2.8 KiB
Python
#!/usr/bin/env python3
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from copy import copy
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from typing import Optional
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from dataclasses import dataclass
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@dataclass
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class Block:
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fid: Optional[int]
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length: int
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puzzle = []
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with open("day09") as f:
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puzzle = list(map(int, f.readline().strip()))
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fs = []
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def fill_fs():
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fid = 0
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for i,e in enumerate(puzzle):
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if i%2==0: # file
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fs.append(Block(fid, e))
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fid += 1
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else: # gap
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fs.append(Block(None, e))
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def find_gaps():
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gaps = []
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for i,b in enumerate(fs):
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if b.fid is None: gaps.append((i, b))
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return gaps
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def find_files():
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files = []
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for i,b in enumerate(fs):
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if b.fid is not None: files.append((i, b))
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return files
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def checksum():
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checksum = 0
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idx = 0
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for b in fs:
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if b.fid is None:
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for i in range(b.length): idx += 1
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else:
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for i in range(b.length):
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checksum += b.fid*idx
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idx += 1
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return checksum
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def part1():
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while True:
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gaps = find_gaps()
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if not gaps: break
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if gaps[-1][0] == len(fs)-1: # free block at end
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del fs[-1]
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continue
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files = find_files()
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next_gap = gaps[0][0]
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next_file = files[-1][0]
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if fs[next_gap].length == fs[next_file].length:
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fs[next_gap] = fs[next_file]
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del fs[-1]
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continue
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if fs[next_gap].length > fs[next_file].length:
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gap_length = fs[next_gap].length
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file_length = fs[next_file].length
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fs.insert(next_gap, fs[next_file])
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fs[next_gap+1].length = gap_length-file_length
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del fs[-1]
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continue
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if fs[next_gap].length < fs[next_file].length:
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gap_length = fs[next_gap].length
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file_length = fs[next_file].length
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fid = fs[next_file].fid
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fs[next_file].length = file_length - gap_length
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fs[next_gap] = Block(fid=fid, length=gap_length)
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continue
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fill_fs()
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part1()
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print(checksum())
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def part2():
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files = list(reversed(find_files()))
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for i,file in enumerate(files):
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gaps = find_gaps()
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if not gaps: break
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file_idx = fs.index(file[1])
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for gap in gaps:
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if gap[0] >= file_idx:
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break
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if gap[1].length == file[1].length:
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fs[file_idx] = Block(fid=None, length=file[1].length)
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fs[gap[0]] = file[1]
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break
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if gap[1].length > file[1].length:
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gap_length = gap[1].length
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file_length = file[1].length
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fs[file_idx] = Block(fid=None, length=file[1].length)
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fs.insert(gap[0], file[1])
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fs[gap[0]+1].length = gap_length-file_length
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break
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fill_fs()
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part2()
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print(checksum()) |