A21105. 对如下结构的树，执行 travel 函数，输出结果是 1 2 3 4 5 。（ ） 1 / \ 2 3 / \ 4 5class Node: def __init__(self, v): self.val = v self.left = None self.right = None def travel(root): if not root: return stack = [] stack.ap…

对如下结构的树，执行 travel 函数，输出结果是   1 2 3 4 5 。（    ）

    1
   / \
  2   3
 / \
4  5

class Node:
    def __init__(self, v):
        self.val = v
        self.left = None
        self.right = None

def travel(root):
    if not root:
        return
    stack = []
    stack.append(root)

    while stack:
        cur = stack.pop()
        print(cur.val, end=" ")
        if cur.right:
            stack.append(cur.right)
        if cur.left:
            stack.append(cur.left)

if __name__ == "__main__":
    root = Node(1)
    root.left = Node(2)
    root.right = Node(3)
    root.left.left = Node(4)
    root.left.right = Node(5)
    travel(root)