Longest Substring JavaScript - LeetCode Solution

longest-substring.js

// Given a string, find the length of the longest substring without repeating characters.

// Examples:

// Given "abcabcbb", the answer is "abc", which the length is 3.

// Given "bbbbb", the answer is "b", with the length of 1.

// Given "pwwkew", the answer is "wke", with the length of 3. Note that the answer must be a substring, "pwke" is a subsequence and not a substring.




var lengthOfLongestSubstring = function(s) {
    
    let map = {}
    let start = 0
    let maxLen = 0
    let arr = s.split('')
    
    for (i=0; i < s.length; i++) {
        let current = map[arr[i]]
        if (current!=null && start <= current) {
            start = current + 1
        } else {
            maxLen = Math.max(maxLen, i - start + 1)
        }
        
        map[arr[i]] = i
    }
    
    return maxLen
    
    
};

let str = "abcabcbbb";
let seen = {};
let start = 0;
let maxLength = 0;

[...str].map((itm, i) => {
if(itm in seen && start <= seen[itm]) {
start = seen[itm];
maxLength = Math.max(i - start, maxLength)
}
seen[itm] = i
})

console.log(maxLength)