前序(Pre-order)

• 根-左-右

  def preorder(self,root):
    if root:
        self.traverse_path.append(root.val)
        self.preorder(root.left)
        self.preorder(root.right)

中序(In-order)

• 左-根-右

  def inorder(self,root):
    if root:
        self.inorder(root.left)
        self.traverse_path.append(root.val)
        self.inorder(root.right)

后序(Post-order)

• 左-右-根

  def postorder(self,root):
    if root:
        self.postorder(root.left)
        self.postorder(root.right)
        self.traverse_path.append(root.val)

深度优先(DFS)

visited = set()
def dfs(node,visited):
    if node in visited:
        return
    visited.add(node)
    # 便利
    for next_node in node.Children():
        if not next_node in visited:
            dfs(next_node,visited)     

广度优先(BFS)

def bfs(graph,start,end):
    queue = []
    queue.append([start])
    visited.add(start)

    while queue:
        node = queue.pop()
        visited.add(node)

        process(node)
        nodes = generate_related_nodes(node)
        queue.push(nodes)