JS - getting the longest non-repeating character substring from a string

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I am trying to solve a task on the leetcode site. My approach to solving this problem was to iterate over a string, and then fill first one array until I find a repeating character, and then start filling another array, until I find a repeating character there as well. Once I would have two filled arrays, I would compare them and keep the longer one, until I am done with iteration. But with these approach I end up checking a lot of things and not sure what to do when I have the secondArray filled and I am still doing the subiteration, to avoid filling the firstArray as well. In general this code is to cumbersome, and I am not sure anymore how should I solve this?

s = "anviaj"
s = "eeydgwdykpv"

var lengthOfLongestSubstring = function(s) {
    let firstArray = [];
    let secondArray = [];
    let firstArrayFull = false;
    let secondArrayFull = false;
    let subIterationFinished = false;
    if (s.length == 1)
            return s;
    for (var i = 0; i < s.length -1; i++) {
        if (!firstArrayFull) {
            firstArray.push(s.charAt(i));
        } else if (!secondArrayFull) { secondArray.push(s.charAt(i)); } 
        for (let j = i + 1; j < s.length; j++) {
            if (j + 1 == s.length) { 
                subIterationFinished = true;
                checkArrays();
            }  
            if (!firstArrayFull && !firstArray.includes(s.charAt(j))) {
                if (secondArrayFull && !subIterationFinished) {
                   firstArray = firstArray;
                } else {
                   firstArray.push(s.charAt(j));
                }

            } else { 
                firstArrayFull = true;
                if (secondArrayFull) {
                    checkArrays();
                }
            } 
            if (firstArrayFull && secondArray.length != 0 && secondArray.includes(s.charAt(j))) { 
                secondArrayFull = true;
                checkArrays();
             }
            if (firstArrayFull && secondArray.length != 0 && !secondArray.includes(s.charAt(j))) {
                secondArray.push(s.charAt(j));
            }
        }
    }

    function checkArrays() {
        if (secondArray.length > firstArray.length) {
            firstArray = [];
            firstArrayFull = false;
            secondArrayFull = true;
        } else {
            secondArray = [];
            secondArrayFull = false;
            firstArrayFull = true;
        }
    }

    return secondArray.length > firstArray.length ? secondArray : firstArray;
};

console.log(lengthOfLongestSubstring(s));
javascript
4 Answers

This is a valid, O(n) solution which only constructs the final string once, tested against a 20.000 length string (it should be still fast with a million characters, but stackoverflow limits input to 30K characters).

/**
 * @param {string} s
 * @return {number}
 */
var lengthOfLongestSubstring = function(s) {
    var l = 0;
    var r = 0;
    var maxL = 0;
    var maxR = 0;
    var length = () => r - l;
    var maxLength = () => maxR - maxL;
    var keys = {};
    while (r < s.length) {
        if (s[r] in keys) {
            var newL = keys[s[r]] + 1;
            for (var i = l; i < newL; i++) {
                delete keys[s[i]];
            }
            if (maxLength() < length()) {
                maxL = l;
                maxR = r;
            }
            l = newL;
        }
        keys[s[r]] = r;
        r = r + 1;
    }

    if (maxLength() < length()) {
        maxL = l;
        maxR = r;
    }
    
    return maxLength();
};

console.log(lengthOfLongestSubstring("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"))

user_28323980

well this is challenging but i figure it out

here is an O(n) solution. cant do better then this

function lengthOfLongestSubstring(str) {
    var currentLength = 0;
    var result = 0;
    var keys = {};
    for (var i in str) {

        if (keys[str[i]] === true) {
            currentLength = 0;
            keys = {};
        }

        keys[str[i]] = true;
        currentLength++;
        if (currentLength > result) {
            result = currentLength;
        }

    }
    return result
}

console.log(lengthOfLongestSubstring("bbbbb"));
console.log(lengthOfLongestSubstring("abcdaajkljl"));
console.log(lengthOfLongestSubstring("pwwkew"));
console.log(lengthOfLongestSubstring("ysbghjjrfumqjpyktddsnxftvdqgxzlvrneaynufhgyqxwaqzelmbsiyxaubrqvguvehpmrykhvikkqzwttg"));

user_85852020

Use two variable, one to keep track of the longest substring and the other to keep track of current longest substring without repetition. Iterate through your string. Check if the current word contains the current character.

If it contains, then checks the length of current word with the longest substring. If it is greater, the update the longest substring.

Update the current word from the last seen index till the length of the current word.

Continue till end of your input string.

var lengthOfLongestSubstring = function(s) {
    var longestSubstring = '';
    var currentWord = '';
    for(var i = 0 ; i < s.length ; i++){
      var foundIndex = currentWord.indexOf(s[i]);
      if(foundIndex > -1){
        if(longestSubstring.length < currentWord.length)
          longestSubstring = currentWord;
        currentWord = currentWord.slice(foundIndex+1);
      }
      currentWord += s[i];
    }
  return longestSubstring.length < currentWord.length ? currentWord.length : longestSubstring.length;
};

console.log(lengthOfLongestSubstring("bbbbb"));
console.log(lengthOfLongestSubstring("abcdaajkljl"));
console.log(lengthOfLongestSubstring("pwwkew"));
console.log(lengthOfLongestSubstring("ysbghjjrfumqjpyktddsnxftvdqgxzlvrneaynufhgyqxwaqzelmbsiyxaubrqvguvehpmrykhvikkqzwttg"));

user_47584940

Can use String#includes() to check if your substring has duplicates

s = "anviaj"
s1 = "eeydgwdykpv"

function findLongest(str) {
  // reduce() iterates array created from split input and returns longest sub string
  return str.split('').reduce((a,c,i)=>{ 
    // start our substring using first character of str 
    let sub = str[0], j = 0; 
    // sub.includes(char) returns true if char already in sub string  
    while (++j < str.length && !sub.includes(str[j])) {
      // no duplicate so add char to substring
      sub += str[j];      
    }
    // remove first character from input string each iteration    
    str = str.slice(1);
    // replace current longest if applicable
    return  sub.length > a.length ? sub : a;
  },'');
}

console.log(findLongest(s))
console.log(findLongest(s1))

user_11759660
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