Depth First Search Traversal

Given a graph with n vertices and edges, perform DFS starting from vertex start. Return the DFS traversal order.

Examples
Input: [4,[[0,1],[0,2],[1,2],[2,3]],0]
Output: [0,1,2,3]
Hints

Depth First Search Traversal

Given a graph with n vertices and edges, perform DFS starting from vertex `start`. Return the DFS traversal order.