Challenge: Implement Depth-First Search

Statement

Given a directed graph represented by an adjacency list graph and an integer source, representing the start vertex of the graph, return an array of integers, result that shows the order of depth-first traversal starting from the specified source vertex.

Constraints

• $1$ $\leq$graph.length $\leq$$10^3$

• $-10^3$ $\leq$graph[i][j] $\leq$$10^3$

Examples