# 1647. Minimum Deletions to Make Character Frequencies Unique

#### Medium

***

A string `s` is called **good** if there are no two different characters in `s` that have the same **frequency**.

Given a string `s`, return *the **minimum** number of characters you need to delete to make* `s` ***good**.*

The **frequency** of a character in a string is the number of times it appears in the string. For example, in the string `"aab"`, the **frequency** of `'a'` is `2`, while the **frequency** of `'b'` is `1`.

 

**Example 1:**

```
Input: s = "aab"
Output: 0
Explanation: s is already good.
```

**Example 2:**

```
Input: s = "aaabbbcc"
Output: 2
Explanation: You can delete two 'b's resulting in the good string "aaabcc".
Another way it to delete one 'b' and one 'c' resulting in the good string "aaabbc".
```

**Example 3:**

```
Input: s = "ceabaacb"
Output: 2
Explanation: You can delete both 'c's resulting in the good string "eabaab".
Note that we only care about characters that are still in the string at the end (i.e. frequency of 0 is ignored).
```

 

**Constraints:**

* `1 <= s.length <= 105`
* `s` contains only lowercase English letters.

```python
class Solution:
    def minDeletions(self, s: str) -> int:
        d = self.getFrequencies(s)
        freq = list(d.values())
        result = 0
        for index in range(len(freq)):
            f = freq[index]
            while f > 0 and f in (freq[:index] + freq[index+1:]):
                f -= 1
                result += 1
            freq[index] = f
        return result
    
    def getFrequencies(self, s:str):
        d = defaultdict(int)
        for char in list(s):
            d[char] += 1
        return d
```