Leetcode--Longest Substring Without Repeating Characters

class Solution {
public:
    int lengthOfLongestSubstring(string s) {
        int n = s.length();
        int i = 0, j = 0;
        int max_length = 0;
        int curr_length = 0;
        bool exit[256] = {false};
        while(j<n){
            if(!exit[s[j]]){
                exit[s[j]] = true;
                j++;
            }
            else{
                while(s[i] != s[j]){
                    exit[s[i]] = false;
                    i++;
                }
                i++;
                j++;
            }
            curr_length = j - i;
            max_length = max_length > curr_length ? max_length : curr_length;
            
        }  
        return max_length;      
    }
};