#451

Sort Characters By Frequency

pupil · 490 · lc medium +27 · verified · 75.1% accepted · 9,176 likes · top 86%

⚑ Frequency Counting ⚑ Bucket / Counting Sort

Description

Given a string s, rearrange its characters in decreasing order of frequency. Characters with equal frequency may be placed in any relative order. Return any valid rearrangement.

Example 1:

Input: s = "tree"

Output: "eert"

Explanation: 'e' appears twice while 'r' and 't' both appear once.

So 'e' must appear before both 'r' and 't'. Therefore "eetr" is also a valid answer.

Example 2:

Input: s = "cccaaa"

Output: "aaaccc"

Explanation: Both 'c' and 'a' appear three times, so both "cccaaa" and "aaaccc" are valid answers.

Note that "cacaca" is incorrect, as the same characters must be together.

Example 3:

Input: s = "Aabb"

Output: "bbAa"

Explanation: "bbaA" is also a valid answer, but "Aabb" is incorrect.

Note that 'A' and 'a' are treated as two different characters.

Code

1

2

3

class Solution:
    def frequencySort(self, s: str) -> str:

class Solution:
    def frequencySort(self, s: str) -> str: