Longest Substring Without Repeating Characters

longestSubstringWithoutRepeating.js

/**
 * @param {string} s
 * @return {number}
 */
var lengthOfLongestSubstring = function(s) {
    let verifier = {};
    let i = 0;
    let j = i+1;
    let max = 1;

    if(s.length == 0) return 0;

    while(j < s.length) {
        if(s[i] != s[j] && !verifier[s[j]]) {
            verifier[s[j]] = s[j];
            max = Math.max(max, j-i + 1);
            j++;
        } else {
            i++;
            j = i+1;
            verifier = {};
        }
    }

    return max;
};

// Run a loop keeping 2 pointers, one at start (i) and the other at start + 1 (j)
// If the characters at current iterations not same and the character at j not in the object 
// then add it to the object and increse j by 1
// if any of these conditions fail, increase i by 1 and make j = i + 1 and empty the object
// return the max of i-j+1 and current max

// Time: O(n)
// Space: O(min(n, m))