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99 lines
3.0 KiB
99 lines
3.0 KiB
"""
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Advent of Code 2021 - Day 01
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Run with:
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python puzzles/day01.py inputs/day01.txt
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"""
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import pathlib
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import sys
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from typing import Dict, List, Tuple
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from numpy import sum as np_sum
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from numpy.lib.stride_tricks import sliding_window_view
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def compare(inputs: List[int]) -> Dict[str, int]:
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result = {"increased": 0, "decreased": 0, "no change": 0, "n/a": 0}
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prev = None
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for cur in inputs:
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status = "no change"
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if prev is None:
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status = "n/a"
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elif cur > prev:
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status = "increased"
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elif cur < prev:
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status = "decreased"
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result[status] += 1
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prev = cur
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return result
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def part1(inputs: List[int]) -> int:
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"""
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Count the number of times a depth measurement increases from the previous measurement. (There is no measurement before the first measurement.) In the example above, the changes are as follows:
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199 (N/A - no previous measurement)
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200 (increased)
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208 (increased)
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210 (increased)
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200 (decreased)
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207 (increased)
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240 (increased)
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269 (increased)
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260 (decreased)
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263 (increased)
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In this example, there are 7 measurements that are larger than the previous measurement.
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"""
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return compare(inputs).get("increased", 0)
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def part2(inputs: List[int]) -> int:
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"""
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Start by comparing the first and second three-measurement windows. The measurements in the first window are marked A (199, 200, 208); their sum is 199 + 200 + 208 = 607. The second window is marked B (200, 208, 210); its sum is 618. The sum of measurements in the second window is larger than the sum of the first, so this first comparison increased.
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Your goal now is to count the number of times the sum of measurements in this sliding window increases from the previous sum. So, compare A with B, then compare B with C, then C with D, and so on. Stop when there aren't enough measurements left to create a new three-measurement sum.
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In the above example, the sum of each three-measurement window is as follows:
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A: 607 (N/A - no previous sum)
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B: 618 (increased)
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C: 618 (no change)
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D: 617 (decreased)
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E: 647 (increased)
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F: 716 (increased)
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G: 769 (increased)
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H: 792 (increased)
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In this example, there are 5 sums that are larger than the previous sum
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"""
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inputs = np_sum(sliding_window_view(inputs, window_shape=3), axis=1)
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return compare(inputs).get("increased", 0)
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def parse(inputs: str) -> List[int]:
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"""Parse the input string"""
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return [int(line) for line in inputs.split()]
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def solve(path: str) -> Tuple[int, int]:
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"""Solve the puzzle"""
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puzzle_input = parse(pathlib.Path(path).read_text().strip())
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part1_result = part1(puzzle_input)
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part2_result = part2(puzzle_input)
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return part1_result, part2_result
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def main() -> None:
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for path in sys.argv[1:]:
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print(f"Input File: {path}")
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part1_result, part2_result = solve(path)
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print(f"Part 1 Result: {part1_result}")
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print(f"Part 2 Result: {part2_result}")
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if __name__ == "__main__":
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main()
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