Is Goal Parser Interpretation easy or hard?

Goal Parser Interpretation is rated Easy. The problem focuses on recognizing fixed string patterns and implementing a clean linear scan, making it a common beginner-friendly question for practicing string manipulation.

Goal Parser Interpretation Python/Java solution

In Python or Java, the typical solution iterates through the string and appends interpreted tokens to a result builder. Python often uses a list or string concatenation, while Java typically uses StringBuilder. Both implementations run in O(n) time and O(n) space.

How to solve Goal Parser Interpretation in O(n)?

Traverse the string with an index pointer. When you see 'G', append 'G' to the result. If you encounter '(', check whether the next characters form '()' or '(al)' and append 'o' or 'al' respectively. Move the pointer forward by the length of the matched token. This processes the entire string in one pass.

What is the best approach for Goal Parser Interpretation?

The best approach is a single-pass string scan. Iterate through the command string and interpret tokens as you encounter them: 'G' stays 'G', '()' becomes 'o', and '(al)' becomes 'al'. This method runs in O(n) time and uses O(n) space for the output string while keeping the logic simple and interview-friendly.

Is Goal Parser Interpretation asked at Google/Amazon/Meta?

Goal Parser Interpretation is categorized as an easy string parsing problem. Similar string manipulation and token parsing questions appear in interviews at companies like Amazon, Google, and Meta, especially in early interview rounds to test basic problem-solving and coding clarity.

What data structure is used in Goal Parser Interpretation?

The problem primarily uses basic string operations. Most solutions build the result using a mutable string builder or list buffer, then convert it to a final string. No advanced data structures are required beyond simple indexing and concatenation.

What is the time complexity of Goal Parser Interpretation?

The optimal solution runs in O(n) time, where n is the length of the command string. Each character is examined at most once while parsing patterns like '()', '(al)', or 'G'. The space complexity is O(n) because the interpreted output string must be stored.

Description Hints 1 Solution Video 2:21

1678. Goal Parser Interpretation

Easy88.0% acceptance1 company

You own a Goal Parser that can interpret a string command. The command consists of an alphabet of "G", "()" and/or "(al)" in some order. The Goal Parser will interpret "G" as the string "G", "()" as the string "o", and "(al)" as the string "al". The interpreted strings are then concatenated in the original order.

Given the string command, return the Goal Parser's interpretation of command.

Example 1:

Input: command = "G()(al)"
Output: "Goal"
Explanation: The Goal Parser interprets the command as follows:
G -> G
() -> o
(al) -> al
The final concatenated result is "Goal".

Example 2:

Input: command = "G()()()()(al)"
Output: "Gooooal"

Example 3:

Input: command = "(al)G(al)()()G"
Output: "alGalooG"

Constraints:

1 <= command.length <= 100
command consists of "G", "()", and/or "(al)" in some order.

Asked at 1 company

Google

Topics

String

Hints open one at a time

Hint 1

You need to check at most 2 characters to determine which character comes next.

2:21

Still stuck?Read 4 approaches, or watch a walkthrough.

Open solution

LanguageLoading editor…

1class Solution:
2    def interpret(self, command: str) -> str:
3        

Starter codePython 3Spaces: 4

Examples

Case 1Case 2Case 3

Input

"G()(al)"

Input

"G()()()()(al)"

Input

"(al)G(al)()()G"

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