112 lines
3.7 KiB
Python
112 lines
3.7 KiB
Python
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# https://adventofcode.com/2023/day/5
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import sys
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FILE = 'input'
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# 1. part - What is the lowest location number that corresponds to any of the initial seed numbers?
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with open(FILE) as f:
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seeds = list(map(int, f.readline().split()[1:]))
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f.readline() # skip first header
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f.readline() # skip empty line
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maps = []
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map_ranges = []
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for line in f:
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if line == '\n':
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maps.append(map_ranges)
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map_ranges = []
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next(f) # skip next header
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else:
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map_ranges.append(tuple(map(int, line.split())))
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if map_ranges: # add the last mapping if it exists
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maps.append(map_ranges)
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# apply mappings for each seed
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lowest_location = sys.maxsize
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for s in seeds:
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for map_ranges in maps:
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for destination_start, source_start, length in map_ranges:
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# if seed is in range of the mapping
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if source_start <= s <= source_start + length - 1:
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s = destination_start + s - source_start
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break
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# keep only tle lowest location
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lowest_location = min(s, lowest_location)
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print(lowest_location)
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# 2. part - What is the lowest location number that corresponds to any of the initial seed numbers?
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from operator import itemgetter
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def map_seed(s, m):
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destination_start, source_start, _ = m
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return destination_start + s - source_start
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def map_seed_range(seed_range, map_ranges):
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seed_ranges = []
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seed_start, seed_end = seed_range[0], seed_range[1]
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for m in map_ranges:
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source_start, source_end = m[1], m[1] + m[2] - 1
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overlap_start = max(seed_start, source_start)
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overlap_end = min(seed_end, source_end)
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# if overlap exists
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if overlap_start <= overlap_end:
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# keep the seed range before ovelap untouched
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if seed_start <= overlap_start - 1:
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seed_ranges.append((seed_start, overlap_start - 1))
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# map range
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seed_ranges.append((map_seed(overlap_start, m), map_seed(overlap_end, m)))
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# cut off already mapped seed ranges
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if overlap_end + 1 <= seed_end:
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seed_start = overlap_end + 1
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else:
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# empty seed range left
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seed_start = sys.maxsize
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break
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# if we have some seed range left
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if seed_start <= seed_end:
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seed_ranges.append((seed_start, seed_end))
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return seed_ranges
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with open(FILE) as f:
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seeds = list(map(int, f.readline().split()[1:]))
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f.readline() # skip first header
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f.readline() # skip empty line
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maps = []
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map_ranges = []
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for line in f:
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if line == '\n':
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map_ranges.sort(key=itemgetter(1)) # sort by source range start
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maps.append(map_ranges)
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map_ranges = []
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next(f) # skip next header
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else:
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map_ranges.append(tuple(map(int, line.split())))
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if map_ranges: # add the last mapping if it exists
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map_ranges.sort(key=itemgetter(1)) # sort by source range start
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maps.append(map_ranges)
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# transform seed input into seed ranges
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seed_ranges = [(seeds[i], seeds[i] + seeds[i + 1] - 1) for i in range(0, len(seeds), 2)]
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# apply mappings for each seed
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for map_ranges in maps:
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new_seed_ranges = [] # each seed range can be mapped to multiple seed ranges
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for seed_range in seed_ranges:
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new_seed_ranges += map_seed_range(seed_range, map_ranges)
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seed_ranges = new_seed_ranges
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# the minimum starting point within the ranges of seed values
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lowest_location = min(seed_range[0] for seed_range in seed_ranges)
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print(lowest_location)
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