<p>Given a string <code>s</code> and an integer <code>k</code>, return <em>the length of the longest substring of</em> <code>s</code> <em>such that the frequency of each character in this substring is greater than or equal to</em> <code>k</code>.</p>

<p data-pm-slice="1 1 []">if no such substring exists, return 0.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;aaabb&quot;, k = 3
<strong>Output:</strong> 3
<strong>Explanation:</strong> The longest substring is &quot;aaa&quot;, as &#39;a&#39; is repeated 3 times.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;ababbc&quot;, k = 2
<strong>Output:</strong> 5
<strong>Explanation:</strong> The longest substring is &quot;ababb&quot;, as &#39;a&#39; is repeated 2 times and &#39;b&#39; is repeated 3 times.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= s.length &lt;= 10<sup>4</sup></code></li>
	<li><code>s</code> consists of only lowercase English letters.</li>
	<li><code>1 &lt;= k &lt;= 10<sup>5</sup></code></li>
</ul>

class Solution {
public:
    int longestSubstring(string s, int k) {
        /* [a:3]
           [b:2]
           [c:1]
        */
        vector<int> map(26,0);
        for(auto c: s){
            map[c-'a']++;
        }
        for(int sz = s.size(); sz > 0; sz--){
            for(int i = s.size()-1; i >= sz; i--){
                map[s[i]-'a']--;
            }
            //print(map);
            for(int i = 0; i <= s.size() - sz; i++){
                //print(map);
                if(check(map, k)) return sz;
                if(i+sz < s.size()){
                    map[s[i+sz] -'a']++;
                    map[s[i]-'a']--;
                }
            }
            
            for(int i = 0; i < s.size() - sz; i++){
                map[s[i]-'a']++;
            }
        }
        return 0;
    }
    bool check(vector<int>& map, int k){
        for(auto c : map){
            if(c < k && c != 0) return false;
        }
        return true;
    }
    void print(vector<int>& map){
        for(auto c: map){
            cout << c << ",";
        }
        cout<<endl;
    }
};
8291