Think About It

Ask yourself:

$1.$ Does DFS guarantee the shortest path in a maze?

$2.$ What happens if DFS finds a path of length $100$ but a path of length $10$ exists?

$3.$ Why does BFS avoid this problem? Next unit explains why BFS is necessary.

DFS visits cells in depth-first order. It might go deep into one corner of the grid before finding B. BFS visits all cells at distance $1$ first, then distance $2$, and so on. The first time BFS reaches B, you know no shorter path exists.