872. Leaf-Similar Trees

Consider all the leaves of a binary tree, from left to right order, the values of those leaves form a leaf value sequence.

For example, in the given tree above, the leaf value sequence is (6, 7, 4, 9, 8).

Two binary trees are considered leaf-similar if their leaf value sequence is the same.

Return true if and only if the two given trees with head nodes root1 and root2 are leaf-similar.

 

Example 1:

Input: root1 = [3,5,1,6,2,9,8,null,null,7,4], root2 = [3,5,1,6,7,4,2,null,null,null,null,null,null,9,8]
Output: true

Example 2:

Input: root1 = [1,2,3], root2 = [1,3,2]
Output: false

 

Constraints:

• The number of nodes in each tree will be in the range [1, 200].
• Both of the given trees will have values in the range [0, 200].

---

#https://leetcode.com/problems/leaf-similar-trees/description/

'''
1. 아이디어 :
    1) dfs로 풀기.
2. 시간복잡도 :
    1) O(n)
3. 자료구조 :
    1) dfs
'''


# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def leafSimilar(self, root1: Optional[TreeNode], root2: Optional[TreeNode]) -> bool:


        def dfs(node,nums):
            if node:
                if node.left==None and node.right==None:
                    nums.append(node.val)
                if node.left:
                    dfs(node.left,nums)
                if node.right:
                    dfs(node.right, nums)
            return nums

        return dfs(root1,[]) == dfs(root2,[])