Question

22

longest substring of non repeating characters javascript

rated 0 times [ 27] [ 5] / answers: 1 / hits: 20930 / 7 Years ago, fri, march 24, 2017, 12:00:00

The problems asks given a string, find the longest non-repeating sub-string without repeating characters. I am a little stumped why returning my code is not working for the string dvdf for example. Here is my code :

function lengthOfLongestSubstring(check) {

    var letters = check.split();

    var max = 0;

    var result = [];

    for (var i = 0; i < letters.length; i++) {

        var start = i

        if (result.indexOf(letters[i]) === -1) {

            result.push(letters[i])

        } else {

            i = i - 1

            result = []

        }

        if (max === 0 || max < result.length) {

            max = result.length

        }

    }

    return max

}

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natalyah

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1 Year ago

answered 7 Years ago havenbilliec · Accepted Answer

This implementation gives the correct result for dvdf.

It adds characters to current_string while there is no duplicate. When you find a duplicate cut current_string to the point of the duplicate. max is the max length current_string had at any time. This logic seems correct to me so I think it's correct.

function lengthOfLongestSubstring(string) {

    var max = 0, current_string = , i, char, pos;



    for (i = 0; i < string.length; i += 1) {

        char = string.charAt(i);

        pos = current_string.indexOf(char);

        if (pos !== -1) {

            // cut dv to v when you see another d

            current_string = current_string.substr(pos + 1);

        }

        current_string += char;

        max = Math.max(max, current_string.length);

    }

    return max;

}



lengthOfLongestSubstring(dvdf); // 3

The value of current_string in each round is , d, dv, vd, vdf.