*366. Find Leaves of Binary Tree

https://leetcode.com/problems/find-leaves-of-binary-tree/

solution

class Solution:
    def findLeaves(self, root: Optional[TreeNode]) -> List[List[int]]:
        ans = []

        def dfs(root):
            if not root:
                return -1

            left = dfs(root.left)
            right = dfs(root.right)
            h = max(left, right) + 1

            if len(ans) == h:
                ans.append([])

            ans[h].append(root.val)
            return h

        dfs(root)
        return ans

时间复杂度：O(n) 空间复杂度：O(h)