Python programming prints the binary tree to multiple lines of code

Topic describes

2 tree is printed from top to bottom, and nodes of the same layer are output from left to right. Each layer outputs 1 row.

Ideas:

1. Save the val value of each node with list

2. Save the nodes of each layer:

Calculate the number of nodes in each layer, so as to ensure that the nodes in each layer are illuminated by pop in the next step

Then pop up each node from left to right in turn, and add the corresponding left node and right node (if any) to list.

The code is as follows:

class TreeNode(): 
  def __init__(self,x): 
    self.val = x 
    self.left = None 
    self.right = None 
def function(root): 
  result = [] 
  if not root: 
    return result 
  A = [] 
  A.append(root) 
  while A: 
    temp = [] 
    size = len(A) 
    for Node in A: 
      temp.append(Node.val) 
    result.append(temp) 
    for i in range(size): 
      node = A.pop(0) 
      if node.left: 
        A.append(node.left) 
      if node.right: 
        A.append(node.right) 
  return result  

conclusion

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