Leetcode 655. Print Binary Tree 두 갈래 트리 문제 풀이 보고서 인쇄

11309 단어 leetcode-java
두 갈래 나무에 인쇄를 요구합니다. 즉, 높이*폭의 행렬에서 인쇄하면 됩니다. 각 하위 나무의 루트는 현재 하위 구간의 중간에 인쇄하면 됩니다.
Print a binary tree in an m*n 2D string array following these rules:

The row number m should be equal to the height of the given binary tree.
The column number n should always be an odd number.
The root node's value (in string format) should be put in the exactly middle of the first row it can be put. The column and the row where the root node belongs will separate the rest space into two parts (left-bottom part and right-bottom part). You should print the left subtree in the left-bottom part and print the right subtree in the right-bottom part. The left-bottom part and the right-bottom part should have the same size. Even if one subtree is none while the other is not, you don't need to print anything for the none subtree but still need to leave the space as large as that for the other subtree. However, if two subtrees are none, then you don't need to leave space for both of them.
Each unused space should contain an empty string "".
Print the subtrees following the same rules.
Example 1:
Input:
     1
    /
   2
Output:
[["", "1", ""],
 ["2", "", ""]]
Example 2:
Input:
     1
    / \
   2   3
    \
     4
Output:
[["", "", "", "1", "", "", ""],
 ["", "2", "", "", "", "3", ""],
 ["", "", "4", "", "", "", ""]]
Example 3:
Input:
      1
     / \
    2   5
   / 
  3 
 / 
4 
Output:

[["",  "",  "", "",  "", "", "", "1", "",  "",  "",  "",  "", "", ""]
 ["",  "",  "", "2", "", "", "", "",  "",  "",  "",  "5", "", "", ""]
 ["",  "3", "", "",  "", "", "", "",  "",  "",  "",  "",  "", "", ""]
 ["4", "",  "", "",  "", "", "", "",  "",  "",  "",  "",  "", "", ""]]
Note: The height of binary tree is in the range of [1, 10].

전반적으로 말하면 첫 번째 dfs는 나무의 높이를 얻었고 두 번째 인쇄는 현재 층의 높이에 따라 상응하는 이동 위치를 계산하면 된다.
# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def printTree(self, root):
        """
        :type root: TreeNode
        :rtype: List[List[str]]
        """
        import math
        def dfs(root, h):
            if root:
                return max(dfs(root.left,h+1), dfs(root.right,h+1))
            else :
                return h
        height = dfs(root, 0)
        width = 2 ** height -1
        #  
        res = [ ["" for j in range(width)] for i in range(height)]
        # dfs print
        def dfs_print(res,root,h,pos):
            if root:
                res[h - 1][pos] = '%d' % root.val
                dfs_print(res, root.left, h+1, pos-2**(height - h - 1))
                dfs_print(res, root.right, h+1, pos+2**(height - h - 1))
        dfs_print(res,root,1,width/2)
        return res

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