Solve 2023 day 05

puzzles/solutions/2023/d05/input_parsing.py

@@ -0,0 +1,69 @@
+import itertools
+import re
+
+
+Mapping = list[tuple[int, int, int]]
+
+
+def get_map_ranges(lines: list[str]) -> Mapping:
+    ranges = []
+    for line in lines:
+        destination_range_start, source_range_start, range_length = map(
+            int, line.split()
+        )
+        difference = destination_range_start - source_range_start
+        source_range_end = source_range_start + range_length
+        ranges.append((source_range_start, source_range_end, difference))
+    return ranges
+
+
+def get_category_mapping(mapping: str) -> tuple[str, Mapping]:
+    lines = mapping.splitlines()
+    source = re.match(r"([a-z]+)", lines[0]).group()
+    ranges = get_map_ranges(lines[1:])
+    return source, ranges
+
+
+def get_all_mappings(mapping_lines: str) -> list[Mapping]:
+    source_to_destination_categories_ranges = []
+    for mapping in mapping_lines.split("\n\n"):
+        source, ranges = get_category_mapping(mapping)
+        source_to_destination_categories_ranges.append(ranges)
+    return source_to_destination_categories_ranges
+
+
+def get_initial_data(
+    input_text: str,
+) -> tuple[list[int], list[Mapping]]:
+    first_line, mapping_lines = input_text.split("\n\n", maxsplit=1)
+    initial_seeds = [int(number) for number in re.findall(r"\d+", first_line)]
+    mappings = get_all_mappings(mapping_lines)
+    return initial_seeds, mappings
+
+
+def get_seeds_ranges(seeds: list[int]) -> list[range]:
+    return [
+        range(seed_number, seed_number + range_length)
+        for seed_number, range_length in itertools.batched(seeds, 2)
+    ]
+
+
+def reverse_mappings(mappings: list[Mapping]) -> list[Mapping]:
+    reversed_mappings = []
+    for name, mapping in reversed(mappings):
+        reversed_mapping = []
+        for mapping_range in mapping:
+            (
+                original_destination_range_start,
+                original_source_range_start,
+                original_difference,
+            ) = mapping_range
+            reversed_range = (
+                original_destination_range_start + original_difference,
+                original_source_range_start + original_difference,
+                -original_difference,
+            )
+            reversed_mapping.append(reversed_range)
+        reversed_mappings.append(reversed_mapping)
+
+    return reversed_mappings

puzzles/solutions/2023/d05/p1.py

@@ -0,0 +1,26 @@
+import math
+import sys
+import input_parsing
+
+
+def get_answer(input_text: str) -> int:
+    """Return the lowest location number hat corresponds to any of the initial seed numbers."""
+    initial_seeds, mappings = input_parsing.get_initial_data(input_text)
+    lowest_location_number = math.inf
+    for seed in initial_seeds:
+        running_value = seed
+        for mapping_ranges in mappings:
+            for source_range_start, source_range_end, difference in mapping_ranges:
+                if source_range_start <= running_value < source_range_end:
+                    running_value += difference
+                    break
+        lowest_location_number = min(lowest_location_number, running_value)
+
+    return lowest_location_number
+
+
+if __name__ == "__main__":
+    try:
+        print(get_answer(sys.argv[1]))
+    except IndexError:
+        pass  # Don't crash if no input was passed through command line arguments.

puzzles/solutions/2023/d05/p2.py

@@ -0,0 +1,33 @@
+import itertools
+import sys
+
+import input_parsing
+
+
+def does_seed_exist(running_value: int, seeds_ranges: list[range]) -> bool:
+    return any(running_value in seed_range for seed_range in seeds_ranges)
+
+
+def get_answer(input_text: str) -> int:
+    """Return the lowest location number hat corresponds to any of the initial seed numbers."""
+    seeds_list, mappings = input_parsing.get_initial_data(input_text)
+    seeds_ranges = input_parsing.get_seeds_ranges(seeds_list)
+    mappings = input_parsing.reverse_mappings(mappings)
+
+    for location_number in itertools.count(start=1):
+        running_value = location_number
+        for mapping_ranges in mappings:
+            for source_range_start, source_range_end, difference in mapping_ranges:
+                if source_range_start <= running_value < source_range_end:
+                    running_value += difference
+                    break
+        print(location_number, running_value)
+        if does_seed_exist(running_value, seeds_ranges):
+            return running_value
+
+
+if __name__ == "__main__":
+    try:
+        print(get_answer(sys.argv[1]))
+    except IndexError:
+        pass  # Don't crash if no input was passed through command line arguments.