fn part2(expense: &[i32], sum: &i32) -> Option<i32> {
    for e in expense {
        let remainder = sum - e;
        if let Some(s) = part1(expense, &remainder) {
            return Some(s * *e);
        }
    }
    None
}
/// find the three entries that sum to 2020 and then multiply those two numbers together.
find the three entries that sum to 2020 and then multiply those two numbers together.
find the three entries that sum to 2020 and then multiply those two numbers together .
fn part2(expense: &[i32], sum: &i32) -> Option<i32> {
    for e in expense {
        let remainder = sum - e;
        if let Some(s) = part1(expense, &remainder) {
            return Some(s * *e);
        }
    }
    None
}
fn part2 ( expense : & [ i32 ] , sum : & i32 ) -> Option < i32 > { for e in expense { let remainder = sum - e ; if let Some ( s ) = part1 ( expense , & remainder ) { return Some ( s * * e ) ; } } None }
find the three entries that sum to 2020 and then multiply those two numbers together.
find the three entries that sum to 2020 and then multiply those two numbers together .
expense
&[i32]
sum
&i32
expense
&[i32]
sum
&i32