//dfs 递归
DFS(Vertex S,Vertex G,HashSet visited, HashMap parents){
    if(S == G) retrun;
    for each of S's neighbors, node , not in visited
        add n to visited set
        add S as node;s parent in parents map
        DFS(node, G, visited, parents)
}

//dfs 循环
DFS(Vertex S,Vertex G){
    Initialize: stack, visited HashSet and parent Hashmap
    Push S onto the stack
    Add S to visited
    while stack is not empty:
        pop node curr from top of stack
        if curr == G return
        for each of curr's neightbors, node, not in visited
            add node to visited set
            add curr as node's parent in parent map
            push node onto stack 
}

// bfs
BFS(Vertex S,Vertex G){
    Initialize: queue, visited HashSet and parent Hashmap
        Enqueue S onto the queue
        Add S to visited
        while queue is not empty:
            dequeue node curr from front of queue
            if curr == G return
            for each of curr's neightbors, node, not in visited
                add node to visited set
                add curr as node's parent in parent map
                enqueue node onto queue 
}