Depth First Search

• DFS Template using explicit stack

boolean DFS(int root, int target) {
    Set<Node> visited;
    Stack<Node> stack;
    add root to stack;
    while (s is not empty) {
        Node cur = the top element in stack;
        remove the cur from the stack;
        return true if cur is target;
        for (Node next : the neighbors of cur) {
            if (next is not in visited) {
                add next to visited;
                add next to stack;
            }
        }
    }
    return false;
}