// Q. Find longest substring without repeating characters function longStr(s) { const seen = new Map(); let start = 0; let maxlen = 0; for (let i = 0; i < s.length; i++) { if (seen.has(s[i])) { start = Math.max(seen.get(s[i]) + 1, start); } seen.set(s[i], i); maxlen = Math.max(i - start + 1, maxlen); } return maxlen; } console.log(longStr("abcab"));