1781. Sum of Beauty of All Substrings

class Solution 
{
    public int beautySum(String s) 
    {
// code here
 int totalBeauty = 0;
        int n = s.length();

        for (int i = 0; i < n; i++) 
        {
            int[] freq = new int[26];                     // frequency array for each substring starting at i
            for (int j = i; j < n; j++)
             {
                freq[s.charAt(j) - 'a']++;                // increment frequency of current character

                int minFreq = Integer.MAX_VALUE;
                int maxFreq = Integer.MIN_VALUE;

                for (int f : freq)  
                {
                    if (f > 0)
                     {
                        minFreq = Math.min(minFreq, f);
                        maxFreq = Math.max(maxFreq, f);
                    }
                }
                
                totalBeauty += (maxFreq - minFreq);
            }
        }
        
        return totalBeauty;
        
    }
}