https://atcoder.jp/contests/abc349/tasks/abc349_d
Rを超えないようにできるだけ飛べばよいです。
// Divide Interval #![allow(non_snake_case)] //////////////////// library //////////////////// fn read<T: std::str::FromStr>() -> T { let mut line = String::new(); std::io::stdin().read_line(&mut line).ok(); line.trim().parse().ok().unwrap() } fn read_vec<T: std::str::FromStr>() -> Vec<T> { read::<String>().split_whitespace() .map(|e| e.parse().ok().unwrap()).collect() } //////////////////// process //////////////////// fn read_input() -> (u64, u64) { let v = read_vec(); let (L, R) = (v[0], v[1]); (L, R) } fn print_intervals(intervals: Vec<(u64, u64)>) { println!("{}", intervals.len()); for (l, r) in intervals.into_iter() { println!("{} {}", l, r) } } fn next(l: u64, R: u64) -> u64 { let mut d: u64 = 1; loop { if l + d > R { d >>= 1; break } else if l % d != 0 { d >>= 1; break } else { d <<= 1 } } l + d } fn F(L: u64, R: u64) -> Vec<(u64, u64)> { let mut intervals: Vec<(u64, u64)> = vec![]; let mut l = L; while l < R { let r = next(l, R); intervals.push((l, r)); l = r } intervals } fn main() { let (L, R) = read_input(); let intervals = F(L, R); print_intervals(intervals) }