Problem: Decode String

Medium

30 min

Explore how to decode strings encoded with repetition patterns by utilizing stacks. This lesson helps you understand the logic for parsing encoded inputs and implementing solutions that handle nested and repeated substrings efficiently within constraints.

Statement

Given an encoded string, return its decoded version. The encoding rule follows the pattern: $k[encoded~string]$ , where the $encoded~string$ is repeated exactly $k$ times.

Note: The $k$ is guaranteed to be a positive integer.

Assume that the input string is always valid, meaning there are no extra spaces, and the square brackets are properly balanced and well-formed. Additionally, assume that the original data contains no digits and that digits are only used for repeating the string.

For example, the input will not contain patterns like $3a$ or $2[4]$ , whereas a valid pattern is $2[aj]3[bax]$ .

Constraints:

$1 \leq$ s.length $\leq 30$
$1 \leq$ $k$ $\leq 100$
s consists of lowercase English letters, digits, and square brackets.

Problem: Decode String

Medium

30 min

Statement

Given an encoded string, return its decoded version. The encoding rule follows the pattern: $k[encoded~string]$ , where the $encoded~string$ is repeated exactly $k$ times.

Note: The $k$ is guaranteed to be a positive integer.

For example, the input will not contain patterns like $3a$ or $2[4]$ , whereas a valid pattern is $2[aj]3[bax]$ .

Constraints:

$1 \leq$ s.length $\leq 30$
$1 \leq$ $k$ $\leq 100$
s consists of lowercase English letters, digits, and square brackets.

Problem: Decode String

Statement

Example

Understand the problem

Figure it out!

Try it yourself

Problem: Decode String

Statement

Example

Understand the problem

Figure it out!

Try it yourself