Code shared from the Rust Playground

peaks.rs

#![allow(unused)]

fn peaks<T: std::cmp::PartialOrd>(values: Vec<T>) -> Vec<usize> {
    values
        .windows(3)
        .enumerate()
        .filter_map(|(i, window)| {
            if window[0] < window[1] && window[1] > window[2] {
                Some(i + 1)
            } else {
                None
            }
        })
        .collect()
}

#[test]
fn single_peak() {
    let values = vec![1, 2, 3, 1];
    assert_eq!(peaks(values), [2]);
}

#[test]
fn multiple_peaks() {
    let values = vec![1, 3, 2, 3, 5, 6, 4];
    assert_eq!(peaks(values), [1, 5]);
}