// find_max_sum_of_three finds 'k' consecutive numbers with the largest sum in a slice.
// It returns an Option containing the maximum sum and a subslice of the numbers.
fn find_max_sum_of_three(numbers: &[i32], k: usize) -> Option<(i32, &[i32])> {
// Validate input parameters: k must be greater than 0 and the slice
// must be at least as long as k
if k == 0 || numbers.len() < k {
return None;
}
// Compute the sum of the initial window of size k using an iterator
let mut current_sum: i32 = numbers[..k].iter().sum();
let mut max_sum = current_sum;
let mut max_start_index = 0;
// Slide the window across the remaining elements:
// Subtract the element leaving on the left, and add the new element on the right.
for i in k..numbers.len() {
current_sum = current_sum - numbers[i - k] + numbers[i];
if current_sum > max_sum {
max_sum = current_sum;
max_start_index = i - k + 1;
}
}
// Return the max sum and the matching subslice safely
Some((max_sum, &numbers[max_start_index..max_start_index + k]))
}
fn main() {
let numbers = vec![4, 2, 0, 8, 7, 5, 1, 3, 9, 6];
let k = 3;
match find_max_sum_of_three(&numbers, k) {
Some((sum, result)) => {
println!("Largest sum: {}", sum);
// Print the numbers space-separated to match the example format
print!("Numbers: ");
for (i, num) in result.iter().enumerate() {
if i > 0 {
print!(" ");
}
print!("{}", num);
}
println!();
}
None => println!("Invalid parameters or slice too short."),
}
}
/*
run:
Largest sum: 20
Numbers: 8 7 5
*/
