Route Between Two Nodes in Graph

题目：

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

分析：

一道简单的bfs题目，注意lintcode上面给出的vector of DirectedGraphNode*本身就是个adj list，不需要再进行转化，直接开queue做就可以。

解法：

class Solution {
public:
    /**
     * @param graph: A list of Directed graph node
     * @param s: the starting Directed graph node
     * @param t: the terminal Directed graph node
     * @return: a boolean value
     */
    bool hasRoute(vector<DirectedGraphNode*> graph,
                  DirectedGraphNode* s, DirectedGraphNode* t) {
        // write your code here
        if (s == t) {
            return true;
        }
        if (s == NULL || t == NULL || graph.size() == 0) {
            return false;
        }

        bool res = false;
        queue<DirectedGraphNode*> Q;
        Q.push(s);
        while (!Q.empty() ) {
            DirectedGraphNode* temp = Q.front();
            Q.pop();
            for (int i = 0; i < temp->neighbors.size(); i++) {
                if (temp->neighbors[i] == t) {
                    res = true;
                    break;
                }
                Q.push(temp->neighbors[i]);
            }
        }
        return res;
    }
};