Longest Substring Without Repeating Characters

Problem

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

Solution Approach

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C++

class Solution {
   public:
    int lengthOfLongestSubstring(string s) {
        vector<int> dict(256, -1);
        int maxLen = 0, start = -1;
        for (int i = 0; i != s.length(); i++) {
            if (dict[s[i]] > start) start = dict[s[i]];
            dict[s[i]] = i;
            maxLen = max(maxLen, i - start);
        }
        return maxLen;
    }
};