# Keys and Rooms

Category

Graphs - DFS

Checkbox

Checkbox

Difficulty

Medium

Index

43

Key Ideas

The key idea to solve this problem is to perform a depth-first search (DFS) or breadth-first search (BFS) starting from the first room and checking if all rooms can be visited.

Problem Number

841

Problem Summary

This problem, numbered 841 in LeetCode, is categorized as a medium-level problem in graph algorithms. The task is to determine whether it is possible to visit every room in a given set of rooms, starting from room 0. The key pitfall in solving this problem is to correctly implement a graph traversal algorithm, such as depth-first search or breadth-first search, and handle the visited rooms to avoid infinite loops.

Solution Summary

To solve the Keys and Rooms problem, we can use a depth-first search (DFS) algorithm. The main idea is to keep track of visited rooms and explore each connected room recursively. We start with the first room and add its keys to a stack. While the stack is not empty, we pop a key from the stack and visit the corresponding room if it hasn't been visited before. We repeat this process until all rooms have been visited or we have no more keys to explore. If all rooms have been visited, we return true; otherwise, we return false. This solution has a time complexity of O(N + E), where N is the number of rooms and E is the total number of keys.

Tags

Depth-First Search

Breadth-First Search

Graph