Data commit

Task/Generator-Exponential/Rust/generator-exponential.rust

@@ -0,0 +1,39 @@
+use std::cmp::Ordering;
+use std::iter::Peekable;
+
+fn powers(m: u32) -> impl Iterator<Item = u64> {
+    (0u64..).map(move |x| x.pow(m))
+}
+
+fn noncubic_squares() -> impl Iterator<Item = u64> {
+    NoncubicSquares {
+        squares: powers(2).peekable(),
+        cubes: powers(3).peekable(),
+    }
+}
+
+struct NoncubicSquares<T: Iterator<Item = u64>, U: Iterator<Item = u64>> {
+    squares: Peekable<T>,
+    cubes: Peekable<U>,
+}
+
+impl<T: Iterator<Item = u64>, U: Iterator<Item = u64>> Iterator for NoncubicSquares<T, U> {
+    type Item = u64;
+    fn next(&mut self) -> Option<u64> {
+        loop {
+            match self.squares.peek()?.cmp(self.cubes.peek()?) {
+                Ordering::Equal => self.squares.next(),
+                Ordering::Greater => self.cubes.next(),
+                Ordering::Less => return self.squares.next(),
+            };
+        }
+    }
+}
+
+fn main() {
+    noncubic_squares()
+        .skip(20)
+        .take(10)
+        .for_each(|x| print!("{} ", x));
+    println!();
+}