Merge Letter Counts

Medium

A string was compressed by writing each letter followed by how many times it repeats in a row. For example, "aaabacc" becomes "a3b1a1c2". You are given such a record in packed. Compress it better: every letter must appear in the record exactly once, with its total count, and the letters must be in alphabetical order. The original order of characters is lost, and that is intended. Return the new record.

Example 1

packed='b2a5b10' → 'a5b12'

The letter b appears twice: 2 + 10 = 12. Sorted alphabetically, that gives "a5b12".

Example 2

packed='c3a1c1a2' → 'a3c4'

a: 1 + 2 = 3, c: 3 + 1 = 4.

Example 3

packed='z1' → 'z1'

Constraints

1 ≤ len(packed) ≤ 6·10⁴
packed is well formed: a lowercase English letter followed by a number
Every number is between 1 and 10⁴ with no leading zeros

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Topics

Hash Table String Counting Sorting

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Input

packed='b2a5b10'

Expected

'a5b12'

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