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1781. Sum of Beauty of All Substrings 👍

  • Time: $O(n^2)$
  • Space: $O(26) = O(1)$
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class Solution {
 public:
  int beautySum(string s) {
    int ans = 0;

    for (int i = 0; i < s.length(); ++i) {
      vector<int> count(26);
      for (int j = i; j < s.length(); ++j) {
        ++count[s[j] - 'a'];
        ans += *max_element(begin(count), end(count)) - getMin(count);
      }
    }

    return ans;
  }

 private:
  int getMin(const vector<int>& count) {
    int mini = INT_MAX;
    for (const int c : count)
      if (c > 0)
        mini = min(mini, c);
    return mini;
  }
};

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class Solution {
  public int beautySum(String s) {
    int ans = 0;

    for (int i = 0; i < s.length(); ++i) {
      int[] count = new int[26];
      for (int j = i; j < s.length(); ++j) {
        ++count[s.charAt(j) - 'a'];
        ans += Arrays.stream(count).max().getAsInt() - getMin(count);
      }
    }

    return ans;
  }

  private int getMin(int[] count) {
    int min = Integer.MAX_VALUE;
    for (final int c : count)
      if (c > 0)
        min = Math.min(min, c);
    return min;
  }
}