longestSubstringWithoutRepeatingCharacters.js

/*
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.

Constraints:
    0 <= s.length <= 5 * 10^4
    s consists of English letters, digits, symbols and spaces.
*/

/**
 * @param {string} s
 * @return {number}
 */
function lengthOfLongestSubstring(s) {
    const map = new Map();
    let maxLen = 0;
    let left = 0;

    for (let right = 0; right < s.length; right++) {
        if (map.has(s[right]) && map.get(s[right]) >= left) {
            left = map.get(s[right]) + 1;
        }
        map.set(s[right], right);
        maxLen = Math.max(maxLen, right - left + 1);
    }
    return maxLen;
}

// Example usage:
console.log(lengthOfLongestSubstring("abcabcbb")); // Output: 3
console.log(lengthOfLongestSubstring("bbbbb"));    // Output: 1
console.log(lengthOfLongestSubstring("pwwkew"));   // Output: 3