Find the seat number mkay

aoc2020/day05/solution.py

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+import sys
+import typing
+
+
+def main() -> int:
+    highest_seat = 0
+
+    taken_seats = set()
+
+    for line in sys.stdin:
+        line = line.strip()
+        if line == "":
+            continue
+
+        seat = _locate_seat(line)
+
+        if seat.number > highest_seat:
+            highest_seat = seat.number
+
+        taken_seats.add(seat.number)
+
+        print(f"bp={line} row={seat.row} column={seat.col} seat={seat.number}")
+
+    seat_number: typing.Optional[int] = None
+    n_found = 0
+
+    for candidate_seat in range(0, (127 * 8) + 1):
+        if candidate_seat in taken_seats:
+            continue
+
+        if (candidate_seat - 1) in taken_seats and (candidate_seat + 1) in taken_seats:
+            seat_number = candidate_seat
+            n_found += 1
+
+    print(f"highest_seat={highest_seat} seat_number={seat_number} n_found={n_found}")
+
+    return 0
+
+
+class Seat:
+    row: int
+    column: int
+
+    def __init__(self, row: int = 0, col: int = 0):
+        self.row = row
+        self.col = col
+
+    @property
+    def number(self) -> int:
+        return (self.row * 8) + self.col
+
+
+def _locate_seat(bp: str) -> Seat:
+    rows = list(range(0, 128))
+    cols = list(range(0, 8))
+
+    row_part = list(bp[:7])
+    col_part = list(bp[7:])
+
+    return Seat(
+        row=_bisect(rows, [{"F": 0, "B": 1}[s] for s in row_part]),
+        col=_bisect(cols, [{"L": 0, "R": 1}[s] for s in col_part]),
+    )
+
+
+def _bisect(initial_selection: typing.List[int], bisections: typing.List[int]) -> int:
+    selection = initial_selection[:]
+
+    for bisection in bisections:
+        halfway = int(len(selection) / 2)
+        selection = [selection[:halfway], selection[halfway:]][bisection]
+
+    return selection[0]
+
+
+if __name__ == "__main__":
+    sys.exit(main())

aoc2020/day05/test-input

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+BFFFBBFRRR
+FFFBBBFRRR
+BBFFBBFRLL

aoc2020/day05/test-output

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+bp=BFFFBBFRRR row=70 column=7 seat=567
+bp=FFFBBBFRRR row=14 column=7 seat=119
+bp=BBFFBBFRLL row=102 column=4 seat=820

aoc2020/day05/test_solution.py

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+import sys
+
+from pathlib import Path
+
+import pytest
+
+from solution import main
+
+
+HERE = Path(__file__).absolute().parent
+
+
+def test_solution(capsys):
+    with (HERE / "test-input").open() as infile:
+        sys.stdin = infile
+        main()
+
+    expected_output = (HERE / "test-output").read_text().splitlines()
+    assert expected_output == [
+        l
+        for l in capsys.readouterr().out.splitlines()
+        if not l.startswith("highest_seat")
+    ]