mirror of
https://github.com/Threnklyn/advent-of-code-go.git
synced 2026-05-18 19:13:27 +02:00
alexchao26
121 lines
3.6 KiB
Python
121 lines
3.6 KiB
Python
from collections import defaultdict
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def part1(input: str) -> int:
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grid = [list(line) for line in input.splitlines()]
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map_antenna_to_coords: dict[str, list[tuple[int, int]]] = defaultdict(list)
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for i in range(len(grid)):
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for j in range(len(grid[0])):
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if grid[i][j] != ".":
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map_antenna_to_coords[grid[i][j]].append((i, j))
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rows = len(grid)
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cols = len(grid[0])
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anti_node_coords: set[tuple[int, int]] = set()
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for _, coords in map_antenna_to_coords.items():
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for i in range(len(coords)):
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c1 = coords[i]
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for j in range(i + 1, len(coords)):
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c2 = coords[j]
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if c1 == c2:
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continue
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rowDiff: int = c2[0] - c1[0]
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colDiff: int = c2[1] - c1[1]
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maybeRow: int = c1[0] - rowDiff
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maybeCol: int = c1[1] - colDiff
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if (
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0 <= maybeRow < rows
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and 0 <= maybeCol < cols
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and (maybeRow, maybeCol) != c1
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and (maybeRow, maybeCol) != c2
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):
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anti_node_coords.add((maybeRow, maybeCol))
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maybeRow: int = c2[0] + rowDiff
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maybeCol: int = c2[1] + colDiff
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if (
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0 <= maybeRow < rows
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and 0 <= maybeCol < cols
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and (maybeRow, maybeCol) != c1
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and (maybeRow, maybeCol) != c2
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):
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anti_node_coords.add((maybeRow, maybeCol))
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return len(anti_node_coords)
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def part2(input: str) -> int:
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grid = [list(line) for line in input.splitlines()]
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map_antenna_to_coords: dict[str, list[tuple[int, int]]] = defaultdict(list)
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for i in range(len(grid)):
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for j in range(len(grid[0])):
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if grid[i][j] != ".":
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map_antenna_to_coords[grid[i][j]].append((i, j))
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rows = len(grid)
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cols = len(grid[0])
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anti_node_coords: set[tuple[int, int]] = set()
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for _, coords in map_antenna_to_coords.items():
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for i in range(len(coords)):
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c1 = coords[i]
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# a more elegant solution would be to calculate the starting point of the antenna's line
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# then do a single loop to find all anti-node coords
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# instead, i'll just go left and right from c1, and add c1 manually
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anti_node_coords.add(c1)
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for j in range(i + 1, len(coords)):
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c2 = coords[j]
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if c1 == c2:
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continue
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rowDiff: int = c2[0] - c1[0]
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colDiff: int = c2[1] - c1[1]
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maybeRow: int = c1[0] - rowDiff
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maybeCol: int = c1[1] - colDiff
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while 0 <= maybeRow < rows and 0 <= maybeCol < cols:
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anti_node_coords.add((maybeRow, maybeCol))
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maybeRow -= rowDiff
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maybeCol -= colDiff
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maybeRow: int = c1[0] + rowDiff
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maybeCol: int = c1[1] + colDiff
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while 0 <= maybeRow < rows and 0 <= maybeCol < cols:
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anti_node_coords.add((maybeRow, maybeCol))
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maybeRow += rowDiff
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maybeCol += colDiff
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return len(anti_node_coords)
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example = """............
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........0...
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.....0......
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.......0....
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....0.......
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......A.....
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............
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............
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........A...
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.........A..
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............
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............"""
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input = open("input.txt").read()
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print(f"part1 example: {part1(example)} want 14")
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print(f"part1: {part1(input)} want 396")
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print(f"part2 example: {part2(example)} want 34")
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print(f"part2: {part2(input)} want 1200")
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