fn unique_characters(input: &str) -> HashSet<char> {
    let mut result = HashSet::new();

    for character in input.chars() {
        assert!(character.is_ascii());

        result.insert(character.to_ascii_lowercase());
    }

    result
}
// O(n) algorithm that returns a set of lower cased characters that is used in the given input
// string.
O(n) algorithm that returns a set of lower cased characters that is used in the given input
string.
O ( n ) algorithm that returns a set of lower cased characters that is used in the given input string .
fn unique_characters(input: &str) -> HashSet<char> {
    let mut result = HashSet::new();
    for character in input.chars() {
        assert!(character.is_ascii());
        result.insert(character.to_ascii_lowercase());
    }
    result
}
fn unique_characters ( input : & str ) -> HashSet < char > { let mut result = HashSet :: new ( ) ; for character in input . chars ( ) { assert ! ( character is_ascii ( ) ) ; result . insert ( character . to_ascii_lowercase ( ) ) ; } result }
O(n) algorithm that returns a set of lower cased characters that is used in the given input
string.
O ( n ) algorithm that returns a set of lower cased characters that is used in the given input string .
input
&str
input
&str