longestSubstringWithoutRepeatingChars.js

/**
 * @param {string} s
 * @return {number}
 */
//first version
// var lengthOfLongestSubstring = function(s) {
//     const arr = s.split("")
//     let letters = []
//     let maxCount = 0
//     let count = 0
//     for (let i = 0; i < arr.length; i++) {
//         const index = letters.findIndex((char) => char === arr[i])
//         if (index !== -1) {
//             i = i - letters.length + index + 1
//             count = 0
//             maxCount = maxCount < letters.length ? letters.length : maxCount
//             letters = []
//         }
//         count++
//         letters.push(arr[i])
//     }
//
//     maxCount = maxCount < count ? count : maxCount
//     return maxCount
// };


const lengthOfLongestSubstring = function(s) {
    const arr = s.split("")
    let letters = []
    let maxCount = 0
    for (let i = 0; i < arr.length; i++) {
        if (letters.includes(arr[i])) {
            letters = letters.slice(letters.indexOf(arr[i]) + 1)
        }
        letters.push(arr[i])

        maxCount = Math.max(maxCount, letters.length)
    }

    return maxCount
};

const example = "abc"

console.log(lengthOfLongestSubstring(example))