Better Compression of String - Solution & Explanation

You are given a string compressed representing a compressed version of a string. The format is a character followed by its frequency. For example, "a3b1a1c2" is a compressed version of the string "aaabacc".

We seek a better compression with the following conditions:

1. Each character should appear only once in the compressed version.
2. The characters should be in alphabetical order.

Return the better compression of compressed.

Note: In the better version of compression, the order of letters may change, which is acceptable.

 

Example 1:

Example 2:

Example 3:

 

Constraints:

• 1 <= compressed.length <= 6 * 104
• compressed consists only of lowercase English letters and digits.
• compressed is a valid compression, i.e., each character is followed by its frequency.
• Frequencies are in the range [1, 104] and have no leading zeroes.