Route Between Two Nodes in Graph

Given a directed graph, design an algorithm to find out whether there is a route between two nodes.

Have you met this question in a real interview?  Yes Example

Given graph:

A----->B----->C \ | \ | \ | \ v ->D----->E

for s = B and t = E, return true

for s = D and t = C, return false

这一到也比较简单，就是考察的递归怎么写，感觉连dfs都不是

代码：

public boolean hasRoute(ArrayList<DirectedGraphNode> graph, DirectedGraphNode s, DirectedGraphNode t) { // write your code here if(graph == null || s == null || t == null) return false; if(s == t) return true; ArrayList<DirectedGraphNode> neighbors = s.neighbors; for(DirectedGraphNode neighbor: neighbors){ if(hasRoute(graph, neighbor, t)){ return true; } } return false; }