Problem
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.
Answer: 4613732
Solution
pub fn sum_even_fib(upper: u32) -> u32
{
let mut fib1 = 1;
let mut fib2 = 1;
let mut result = 0;
let mut summed = 0;
while result < upper {
if (result % 2) == 0 {
summed += result;
}
result = fib1 + fib2;
fib2 = fib1;
fib1 = result;
}
return summed;
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn euler_002() {
assert_eq!(sum_even_fib(4_000_000), 4613732);
}
}