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$ curl repovive.com/roadmaps/graph-theory/depth-first-search-dfs/keys-and-rooms-implementation

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$ curl repovive.com/roadmaps/graph-theory/depth-first-search-dfs/keys-and-rooms-implementation

Repovive

LeetCode 841 Keys and Rooms - Implementation - Depth First Search (DFS) | Graph Theory | Repovive

Repovive.

Graph Theory37 sections · 1633 units81h total

Open in Course

LeetCode 841 Keys and Rooms - Implementation

Coding it

Note: LeetCode gives you rooms which is already an adjacency list.

visited = [false] * n

function dfs(u, rooms):
    visited[u] = true
    for each v in rooms[u]:
        if not visited[v]:
            dfs(v, rooms)

function canVisitAllRooms(rooms):
    n = rooms.length
    visited = [false] * n
    dfs(0, rooms)
    for i from 0 to n - 1:
        if not visited[i]:
            return false
    return true

This runs in $O(V + E)$ time and uses $O(V)$ space.