0917. Reverse Only Letters

https://leetcode.com/problems/reverse-only-letters

Description

Given a string s, reverse the string according to the following rules:

• All the characters that are not English letters remain in the same position.

• All the English letters (lowercase or uppercase) should be reversed.

Return s after reversing it.

Example 1:

**Input:** s = "ab-cd"
**Output:** "dc-ba"

Example 2:

**Input:** s = "a-bC-dEf-ghIj"
**Output:** "j-Ih-gfE-dCba"

Example 3:

**Input:** s = "Test1ng-Leet=code-Q!"
**Output:** "Qedo1ct-eeLg=ntse-T!"

Constraints:

• 1 <= s.length <= 100

• s consists of characters with ASCII values in the range [33, 122].

• s does not contain '\"' or '\\'.

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