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Coding & Algorithms questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master coding & algorithms interviews.

What difficulty level is this interview question?

This is a medium difficulty Coding & Algorithms question, commonly asked during Technical Screen rounds at Molocoads.

What role is this question designed for?

This question is commonly asked for Software Engineer candidates at Molocoads during technical interviews.

Can you visit all rooms and score parentheses? | Molocoads Interview Question

Q: Can you visit all rooms and score parentheses?

The first problem evaluates graph traversal and reachability by modeling rooms and keys as an implicit graph, and it is commonly asked to assess reasoning about connectivity and exploration in graph-theoretic settings; this falls under the algorithms/graph theory domain and emphasizes practical application of traversal techniques.

Problem 1: Visit all locked rooms with keys

There are n rooms labeled 0..n-1. All rooms are locked except room 0.

When you enter room i , you find a set of keys rooms[i] .
Each key is an integer k that unlocks room k .
You may collect and carry all keys you find.

Task: Given rooms: List[List[int]], return true if you can eventually visit every room starting from room 0, otherwise return false.

Input/Output

Input: rooms , where rooms[i] is the list of keys in room i
Output: boolean

Constraints (typical):

1 <= n <= 10^4
0 <= rooms[i].length <= 10^4
Keys are in range 0..n-1 (may include duplicates)

Problem 2: Compute the score of a balanced parentheses string

You are given a balanced parentheses string s consisting only of '(' and ')'.

Define the score recursively:

"()" has score 1
Concatenation: if A and B are balanced, then score(A + B) = score(A) + score(B)
Nesting: if A is balanced, then score("(" + A + ")") = 2 * score(A)

Task: Return score(s).

Input/Output

Input: balanced string s
Output: integer score

Constraints (typical):

1 <= s.length <= 10^5
s is guaranteed balanced

Problem 1: Visit all locked rooms with keys

There are n rooms labeled 0..n-1. All rooms are locked except room 0.

When you enter room i , you find a set of keys rooms[i] .
Each key is an integer k that unlocks room k .
You may collect and carry all keys you find.

Task: Given rooms: List[List[int]], return true if you can eventually visit every room starting from room 0, otherwise return false.

Input/Output

Input: rooms , where rooms[i] is the list of keys in room i
Output: boolean

Constraints (typical):

1 <= n <= 10^4
0 <= rooms[i].length <= 10^4
Keys are in range 0..n-1 (may include duplicates)

Problem 2: Compute the score of a balanced parentheses string

You are given a balanced parentheses string s consisting only of '(' and ')'.

Define the score recursively:

"()" has score 1
Concatenation: if A and B are balanced, then score(A + B) = score(A) + score(B)
Nesting: if A is balanced, then score("(" + A + ")") = 2 * score(A)

Task: Return score(s).

Input/Output

Input: balanced string s
Output: integer score

Constraints (typical):

1 <= s.length <= 10^5
s is guaranteed balanced

Can you visit all rooms and score parentheses?

Quick Overview

Problem 1: Visit all locked rooms with keys

Problem 2: Compute the score of a balanced parentheses string

Submit Your Answer to Earn 20XP

Can you visit all rooms and score parentheses?

Quick Overview

Problem 1: Visit all locked rooms with keys

Problem 2: Compute the score of a balanced parentheses string

Submit Your Answer to Earn 20XP