process-string-with-special-operations-i

You are given a string s consisting of lowercase English letters and the special characters: *, #, and %.

Build a new string result by processing s according to the following rules from left to right:

If the letter is a lowercase English letter append it to result.

A '*' removes the last character from result, if it exists.

A '#' duplicates the current result and appends it to itself.

A '%' reverses the current result.

Return the final string result after processing all characters in s.

Example 1:

Input: s = "a#b%*"

Output: "ba"

Explanation:

i
s[i]
Operation
Current result

0
'a'
Append 'a'
"a"

1
'#'
Duplicate result
"aa"

2
'b'
Append 'b'
"aab"

3
'%'
Reverse result
"baa"

4
'*'
Remove the last character
"ba"

Thus, the final result is "ba".

Example 2:

Input: s = "z*#"

Output: ""

Explanation:

i
s[i]
Operation
Current result

0
'z'
Append 'z'
"z"

1
'*'
Remove the last character
""

2
'#'
Duplicate the string
""

Thus, the final result is "".

Constraints:

1 <= s.length <= 20

s consists of only lowercase English letters and special characters *, #, and %.

process-string-with-special-operations-i

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