0003-longest-substring-without-repeating-characters.ts

function lengthOfLongestSubstring(s: string): number {
    const charSet = new Set();
    let l = 0;
    let res = 0;

    for (let r = 0; r < s.length; r++) {
        while (charSet.has(s[r])) {
            charSet.delete(s[l]);
            l += 1;
        }
        charSet.add(s[r]);
        res = Math.max(res, r - l + 1);
    }
    return res;
}