1781. Sum of Beauty of All Substrings

Problem Link

Description

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The beauty of a string is the difference in frequencies between the most frequent and least frequent characters.

• For example, the beauty of "abaacc" is 3 - 1 = 2.

Given a string s, return the sum of beauty of all of its substrings.

 

Example 1:

Input: s = "aabcb"
Output: 5
Explanation: The substrings with non-zero beauty are ["aab","aabc","aabcb","abcb","bcb"], each with beauty equal to 1.

Example 2:

Input: s = "aabcbaa"
Output: 17

 

Constraints:

• 1 <= s.length <= 500
• s consists of only lowercase English letters.

Solution

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Python3

class Solution:
    def beautySum(self, s: str) -> int:
        n = len(s)
        res = 0
        
        for i in range(n):
            mp = collections.defaultdict(int)
            for j in range(i, n):
                mp[s[j]] += 1
                v = mp.values()
                res += max(v) - min(v)
        
        return res