4.1 Route Between Nodes

For all directed graph problem, I use struct DirectedGraphNode:

struct DirectedGraphNode {
int label;
vector<DirectedGraphNode *> neighbors;
DirectedGraphNode(int x) : label(x) {};
};

Simply BFS traverse Graph:

bool hasRoute(vector<DirectedGraphNode*> graph,
DirectedGraphNode* s, DirectedGraphNode* t) {
// write your code here
queue<DirectedGraphNode*> q;
q.push(s);
while(!q.empty()){
DirectedGraphNode* cur = q.front();
q.pop();
for(auto node : cur->neighbors) q.push(node);
if(cur == t) return true;
}
return false;
}

Note: BFS always first think about queue!