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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.

Note:

• Both of the given trees will have between 1 and 100 nodes.

Solutions (Python)

1. DFS

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def leafSimilar(self, root1: TreeNode, root2: TreeNode) -> bool:
        def getLeaves(root: TreeNode) -> List[int]:
            if not root.left and not root.right:
                return [root.val]
            leaves = []
            if root.left:
                leaves += getLeaves(root.left)
            if root.right:
                leaves += getLeaves(root.right)
            return leaves

        return getLeaves(root1) == getLeaves(root2)