Asked at
Decode String
MediumVerifiedStackString Matching~24 min
Given an encoded string s using the rule k[encoded] (repeat encoded k times, nestable), return the decoded string.
The input arrives as a single string s. Use two stacks: one for repeat counts, one for the string built so far.
Examples
in"3[a]2[bc]"
out"aaabcbc"
a repeats 3 times, bc repeats 2 times.
in"3[a2[c]]"
out"accaccacc"
Inner 2[c] -> cc, so a2[c] -> acc, repeated 3 times.
Constraints
- 1 ≤ s.length ≤ 30
- Encoded as k[encoded], with k a positive integer.
- Input is always valid; no leading zeros on k.
Get help
🔑
Sign in to solve
Sign in to write, run, and submit your solution — and to pick up where your iOS flow left off.