40 lines
997 B
Plaintext
40 lines
997 B
Plaintext
use std::cmp::Ordering;
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use std::iter::Peekable;
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fn powers(m: u32) -> impl Iterator<Item = u64> {
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(0u64..).map(move |x| x.pow(m))
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}
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fn noncubic_squares() -> impl Iterator<Item = u64> {
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NoncubicSquares {
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squares: powers(2).peekable(),
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cubes: powers(3).peekable(),
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}
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}
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struct NoncubicSquares<T: Iterator<Item = u64>, U: Iterator<Item = u64>> {
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squares: Peekable<T>,
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cubes: Peekable<U>,
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}
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impl<T: Iterator<Item = u64>, U: Iterator<Item = u64>> Iterator for NoncubicSquares<T, U> {
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type Item = u64;
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fn next(&mut self) -> Option<u64> {
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loop {
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match self.squares.peek()?.cmp(self.cubes.peek()?) {
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Ordering::Equal => self.squares.next(),
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Ordering::Greater => self.cubes.next(),
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Ordering::Less => return self.squares.next(),
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};
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}
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}
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}
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fn main() {
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noncubic_squares()
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.skip(20)
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.take(10)
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.for_each(|x| print!("{} ", x));
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println!();
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}
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