61 lines
1.7 KiB
Python
61 lines
1.7 KiB
Python
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import sys
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def main():
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raw_line = sys.stdin.read().strip()
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line = [int(x) for x in raw_line]
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blocks = []
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file_id = 0
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is_file_len = True
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for num in line:
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if is_file_len:
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if num > 0:
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blocks.extend([str(file_id)] * num)
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file_id += 1
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else:
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if num > 0:
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blocks.extend(["."] * num)
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is_file_len = not is_file_len
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# Move whole files in order of decreasing file ID
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max_file_id = file_id - 1
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for fid in range(max_file_id, -1, -1):
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file_positions = [i for i, b in enumerate(blocks) if b == str(fid)]
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if not file_positions:
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continue
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file_len = len(file_positions)
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leftmost_file_index = min(file_positions)
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candidate_spans = []
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free_count = 0
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start_index = 0
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for i in range(leftmost_file_index):
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if blocks[i] == '.':
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if free_count == 0:
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start_index = i
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free_count += 1
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if free_count == file_len:
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candidate_spans.append((start_index, i))
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else:
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free_count = 0
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if not candidate_spans:
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continue
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span_start, span_end = candidate_spans[0]
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for pos in file_positions:
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blocks[pos] = '.'
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for i in range(span_start, span_start + file_len):
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blocks[i] = str(fid)
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# Compute checksum
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checksum_parts = []
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for idx, val in enumerate(blocks):
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if val != ".":
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checksum_parts.append(idx * int(val))
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print("System Checksum Found: " + str(sum(checksum_parts)))
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if __name__ == "__main__":
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main()
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