1647. Minimum Deletions to Make Character Frequencies Unique - LeetCode

from collections import Counter


class Solution:
    def minDeletions(self, s: str) -> int:
        result = 0
        used: set[int] = set()
        for c in Counter(s).values():
            while c and c in used:
                result += 1
                c -= 1
            used.add(c)
        return result