// A function that finds the two largest elements in any ordered slice.
// It returns an Option containing a tuple of references to (largest, second_largest).
// Using references (&T) avoids cloning elements and works for any type implementing Ord.
fn find_two_largest<T: Ord>(slice: &[T]) -> Option<(&T, &T)> {
// A slice must have at least 2 elements to find a second largest.
if slice.len() < 2 {
return None;
}
// Initialize largest and second largest based on the first two elements
let (mut largest, mut second) = if slice[0] > slice[1] {
(&slice[0], &slice[1])
} else {
(&slice[1], &slice[0])
};
// Iterate through the rest of the slice starting from index 2
for item in &slice[2..] {
if item > largest {
// Found a new absolute maximum; the old maximum becomes the second largest
second = largest;
largest = item;
} else if item > second {
// Item is greater than second, but not largest
second = item;
}
}
Some((largest, second))
}
fn main() {
// Define the vector with the provided data
let data = vec![3, 4, 9, 6, 7, 1, 2, 5];
// Call our function and handle the Option result idiomatically using match
match find_two_largest(&data) {
Some((largest, second_largest)) => {
println!("Dataset: {:?}", data);
println!("The largest element is: {}", largest);
println!("The second largest element is: {}", second_largest);
}
None => {
println!("Error: The collection must contain at least two elements.");
}
}
}
/*
run:
Dataset: [3, 4, 9, 6, 7, 1, 2, 5]
The largest element is: 9
The second largest element is: 7
*/
