diff --git a/2016/d20/ex2/ex2.py b/2016/d20/ex2/ex2.py new file mode 100755 index 0000000..cdffb43 --- /dev/null +++ b/2016/d20/ex2/ex2.py @@ -0,0 +1,44 @@ +#!/usr/bin/env python + +import sys +from typing import NamedTuple + + +class Interval(NamedTuple): + start: int + end: int + + @classmethod + def from_str(cls, input: str) -> "Interval": + start, end = input.split("-") + return cls(int(start), int(end)) + + +def solve(input: str) -> int: + def parse(input: str) -> list[Interval]: + return [Interval.from_str(line) for line in input.splitlines()] + + def merge_overlaps(intervals: list[Interval]) -> list[Interval]: + # Sort intervals by start, then merge overlapping ones + intervals = sorted(intervals) + res = [intervals[0]] + for interval in intervals[1:]: + # `+ 1` to merge [0, 2] and [2, 5] + if interval.start <= (res[-1].end + 1): + res[-1] = Interval(res[-1].start, max(interval.end, res[-1].end)) + else: + res.append(interval) + return res + + intervals = parse(input) + intervals = merge_overlaps(intervals) + return (1 << 32) - sum((end - start + 1) for start, end in intervals) + + +def main() -> None: + input = sys.stdin.read() + print(solve(input)) + + +if __name__ == "__main__": + main()