Longest Substring Without Repeating Charactersmedium

use std::collections::HashMap;

fn length_of_longest_substring(s: &str) -> usize {
    // TODO: sliding window with a HashMap
    0
}

fn main() {
    println!("{}", length_of_longest_substring("abcabcbb")); // 3
    println!("{}", length_of_longest_substring("bbbbb"));    // 1
    println!("{}", length_of_longest_substring("pwwkew"));   // 3
}