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3. Longest Substring Without Repeating Characters

Problem Statement

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

Solutions

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int lengthOfLongestSubstring(string s) {
    vector<int> table(256, -1);

    int l = 0, ans = 0;
    for (int i = 0; i < s.size(); i++) {
        char c = s[i];
        l = max(table[c] + 1, l);
        ans = max(i - l + 1, ans);
        table[c] = i;
    }
    return ans;
}
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