#655

Print Binary Tree

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tree · depth-first search · breadth-first search · binary tree

Description

Given the root of a binary tree, construct a 0-indexed m x n string matrix res that represents a formatted layout of the tree. The formatted layout matrix should be constructed using the following rules:

- The height of the tree is height and the number of rows m should be equal to height + 1.

- The number of columns n should be equal to 2height+1 - 1.

- Place the root node in the middle of the top row (more formally, at location res[0][(n-1)/2]).

- For each node that has been placed in the matrix at position res[r][c], place its left child at res[r+1][c-2height-r-1] and its right child at res[r+1][c+2height-r-1].

- Continue this process until all the nodes in the tree have been placed.

- Any empty cells should contain the empty string "".

Return the constructed matrix res.

Example 1:

Input: root = [1,2]
Output:
[["","1",""],
["2","",""]]

Example 2:

Input: root = [1,2,3,null,4]
Output:
[["","","","1","","",""],
["","2","","","","3",""],
["","","4","","","",""]]

Solution