3. Longest Substring Without Repeating Characters

Given a string s, find the length of the longest substring without repeating characters.

Example 1:

Input: s = "abcabcbb"
Output: 3
Explanation: The answer is "abc", with the length of 3.

Example 2:

Input: s = "bbbbb"
Output: 1
Explanation: The answer is "b", with the length of 1.

Example 3:

Input: s = "pwwkew"
Output: 3
Explanation: The answer is "wke", with the length of 3.
Notice that the answer must be a substring, "pwke" is a subsequence and not a substring.

Example 4:

Input: s = ""
Output: 0

Constraints:

• 0 <= s.length <= 5 * 104
• s consists of English letters, digits, symbols and spaces.

3. Longest Substring Without Repeating Characters
struct Solution;

use std::collections::HashMap;

impl Solution {
fn length_of_longest_substring(s: String) -> i32 {
let mut hm: HashMap<char, usize> = HashMap::new();
let mut max: usize = 0;
let mut l: usize = 0;
for (r, c) in s.char_indices() {
if let Some(end) = hm.insert(c, r) {
l = usize::max(l, end + 1);
}
max = usize::max(r - l + 1, max);
}
max as i32
}
}

#[test]
fn test() {
let s = " ".to_string();
assert_eq!(Solution::length_of_longest_substring(s), 1);
let s = "abba".to_string();
assert_eq!(Solution::length_of_longest_substring(s), 2);
let s = "abcabcbb".to_string();
assert_eq!(Solution::length_of_longest_substring(s), 3);
let s = "bbbb".to_string();
assert_eq!(Solution::length_of_longest_substring(s), 1);
let s = "pwwkew".to_string();
assert_eq!(Solution::length_of_longest_substring(s), 3);
}