Given a string s encoding repeated substrings in the form k[encoded_string], return the fully decoded string. The integer k is a positive repeat count, brackets may be nested, and plain lowercase letters should appear unchanged in the output.
Example 1:
Input: s = "3[a]2[bc]"
Output: "aaabcbc"
Explanation: "a" is repeated 3 times and "bc" is repeated 2 times.
Example 2:
Input: s = "3[a2[c]]"
Output: "accaccacc"
Explanation: The inner substring "c" is repeated first, then the outer result is repeated 3 times.
1 <= len(s) <= 10^5s consists of lowercase English letters, digits, [ and ]1 <= k <= 10^4 for every repeat count in the input