filter_array_by_contains (playground https://gist.github.com/rust-play/6d697a29901d4b82cc8b184526d4b8f1 )

filter_array_by_contains.rs

#![allow(dead_code)]

// playground: https://gist.github.com/rust-play/6d697a29901d4b82cc8b184526d4b8f1

fn all_postfixes_sorted(arr: &[&str]) -> Vec<String> {
    let mut postfixes: std::collections::HashSet<String> = std::collections::HashSet::new();
    for &w in arr {
        for start_idx in 0..(w.chars().count()) {
            let slice: &str = &w[start_idx..];
            let w = String::from(slice);
            postfixes.insert(w);
        }
    }
    let mut r = postfixes.into_iter().collect::<Vec<String>>();
    r.sort();
    r
}

fn filter_array_by_contains(arr_a: &[&str], arr_b: &[&str]) -> Vec<String> {
    let postfixes = all_postfixes_sorted(arr_b);
    
    let pred = |x: &&str| -> Option<String> {
        let idx = postfixes.partition_point(|y| *y < x.to_string());
        eprintln!("postfixes[idx] = '{:?} vs '{:?}' ", postfixes[idx], x);
        if postfixes[idx].contains(x) {
            Some(x.to_string())
        } else {
            None
        }
    };
    arr_a
    .iter()
    .filter_map(pred)
    .collect()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn examples() {
        assert_eq!(filter_array_by_contains(
            &["xyz", "live", "strong"],
            &["lively", "alive", "harp", "sharp", "armstrong"],
        ), ["live", "strong"]);
        
        assert_eq!(filter_array_by_contains(
            &["live", "strong", "arp"],
            &["lively", "alive", "harp", "sharp", "armstrong"],
        ), ["live", "strong", "arp"]);
        
        assert_eq!(filter_array_by_contains(
            &["tarp", "mice", "bull"],
            &["lively", "alive", "harp", "sharp", "armstrong"],
        ), [] as [&str; 0]);
        
        assert_eq!(filter_array_by_contains(
            &["live", "strong", "arp", "arp"],
            &["lively", "alive", "harp", "sharp", "armstrong"],
        ), ["live", "strong", "arp", "arp"]);
    }
}