Problem
Given a string s, sort it in decreasing order based on the frequency of the characters. The frequency of a character is the number of times it appears in the string.
Return the sorted string. If there are multiple answers, return any of them.
Constraints
1 <= s.length <= 5 * 105 s consists of uppercase and lowercase English letters and digits.
Thinking
- store frequency in a dictionary and sort the items()
from typing import DefaultDict, List
def frequencySort(s: str) -> str:
frequency_dict = DefaultDict(int)
for i in range(len(s)):
frequency_dict[s[i]] += 1
sorted_item = sorted(frequency_dict.items(), key=lambda x: -x[1])
result = []
for letter, frequency in sorted_item:
for i in range(frequency):
result.append(letter)
return "".join(result)
if __name__ == "__main__":
print(frequencySort("cAcacbb"))
