longestSubString.js

/**
Find the longest substring in string. Output the length of the substring

e.g
s = 'ababc'

sub = 3
*/

const s = 'ababc';
const n = s.length;
const map = {};
let sub = 0;

for (let j = 0, i = 0; j < n; j++) {
  if (map[s[j]]) {
    i = Math.max(map[s[j]], i)
  }
  sub = Math.max(j - i + 1, sub)
  map[s[j]] = j + 1
}

console.log(sub)