Section 1Understand Problem
Section 01
Understand the problem
Restate the problem precisely. Interviewers reward candidates who pause, define the contract, and name the guarantees before coding.
Problem statement
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 and that the original data does not contain any digits and that digits are only for those repeat numbers, k.
Example
s = "3[a]2[bc]" → "aaabcbc"
Constraints
1 ≤ s.length ≤ 30 · s consists of lowercase English letters, digits, and '[]' · s is a valid encoded string
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