p2.txt

def path_from_s_to_t(G: directed graph, s: starting point, t: ending point)
    return dfs(G, s, t, "white")

def dfs(G, u, t, color):
    if u is t:
        return True
    found_path_to_t = False
    for all neighbors v in u:
        if color == edge(u, v) and v.prev is None:
            v.prev = u
            if color == "white":
                found_path_to_t ||= dfs(G, v, t, "black")
            else if color == "black":
                found_path_to_t ||= dfs(G, v, t, "white")
    if found_path_to_t is True:
        return True
    else:
        # turn curr node to unvisited
        u.prev = None
        return False