A22261. 下列代码实现了树的深度优先遍历，则横线处应填⼊（ ）。class TreeNode: def __init__(self, x): self.val = x self.left = None self.right = None def dfs1(root): if not root: return temp = [] temp.append(root) while temp: node = te…

下列代码实现了树的深度优先遍历，则横线处应填⼊（    ）。

class TreeNode:
    def __init__(self, x):
        self.val = x
        self.left = None
        self.right = None

def dfs1(root):
    if not root:
        return
    temp = []
    temp.append(root)
    while temp:
        node = temp[-1]
        temp.pop()
        print(node.val, end=" ")
        if node.right:
            temp.append(node.right)
        if node.left:
            temp.append(node.left)

def dfs2(root):
    if not root:
        return
    st = []
    st.append(root)
    while st:
        node = st[-1]
        st.pop()
        print(node.val, end=" ")
        if node.right:
            st.append(node.right)
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