How would I even make this faster?

ProfessorChill · 07-26-2018, 10:46 PM

I did this challenge, because I like learning by doing challenges.
http://i.imgur.com/SZzrXSp.png

But it can clearly go faster, but I'm not sure how I'd do that.

Code:
class Solution
{
    public:
	int lengthOfLongestSubstring(std::string s)
	{
		size_t x;
		int y, result;
		int index[128];

		std::memset(index, 0, sizeof(index));

		result = y = 0;
		for (x = 0; x < s.length(); x++) {
			y = std::max(index[static_cast<int>(s[x])], y);
			result = std::max(result, static_cast<int>(x - y + 1));
			index[static_cast<int>(s[x])] = x + 1;
		}

		return result;
	}
};

Any tips?