Given an encoded string, return its decoded string.
The encoding rule is: k[encoded_string]
, where the encoded_string
inside the square brackets is being repeated exactly k
times. Note that k
is guaranteed to be a positive integer.
You may assume that the input string is always valid; there are no extra white spaces, square brackets are well-formed, etc. Furthermore, you may assume that the original data does not contain any digits and that digits are only for those repeat numbers, k
. For example, there will not be input like 3a
or 2[4]
.
The test cases are generated so that the length of the output will never exceed 105
.
Example 1:
Input: s = "3[a]2[bc]" Output: "aaabcbc"
Example 2:
Input: s = "3[a2[c]]" Output: "accaccacc"
Example 3:
Input: s = "2[abc]3[cd]ef" Output: "abcabccdcdcdef"
Constraints:
1 <= s.length <= 30
s
consists of lowercase English letters, digits, and square brackets'[]'
.s
is guaranteed to be a valid input.- All the integers in
s
are in the range[1, 300]
.