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/*
* Even Fibonacci numbers
* Problem 2
*
* Each new term in the Fibonacci sequence is generated by adding the previous two terms.
* By starting with 1 and 2, the first 10 terms will be:
* 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
* By considering the terms in the Fibonacci sequence whose values do not exceed four million,
* find the sum of the even-valued terms.
*/
struct Fib {
a: u32,
b: u32
}
impl Iterator for Fib {
type Item = u32;
fn next(&mut self) -> Option<u32> {
let c = self.a + self.b;
self.a = self.b;
self.b = c;
return Some(c)
}
}
fn main() {
let fib = Fib { a: 0, b: 1 };
let mut sum = 0;
for f in fib {
if f > 4_000_000 {
break;
}
if f % 2 == 0 {
sum += f;
}
}
println!("{}", sum);
}
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