public class Solution
extends Object
1457 - Pseudo-Palindromic Paths in a Binary Tree\.
Medium
Given a binary tree where node values are digits from 1 to 9. A path in the binary tree is said to be **pseudo-palindromic** if at least one permutation of the node values in the path is a palindrome.
_Return the number of **pseudo-palindromic** paths going from the root node to leaf nodes._
**Example 1:**
**Input:** root = [2,3,1,3,1,null,1]
**Output:** 2
**Explanation:** The figure above represents the given binary tree. There are three paths going from the root node to leaf nodes: the red path [2,3,3], the green path [2,1,1], and the path [2,3,1]. Among these paths only red path and green path are pseudo-palindromic paths since the red path [2,3,3] can be rearranged in [3,2,3] (palindrome) and the green path [2,1,1] can be rearranged in [1,2,1] (palindrome).
**Example 2:**
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**Input:** root = [2,1,1,1,3,null,null,null,null,null,1]
**Output:** 1
**Explanation:** The figure above represents the given binary tree. There are three paths going from the root node to leaf nodes: the green path [2,1,1], the path [2,1,3,1], and the path [2,1]. Among these paths only the green path is pseudo-palindromic since [2,1,1] can be rearranged in [1,2,1] (palindrome).
**Example 3:**
**Input:** root = [9]
**Output:** 1
**Constraints:**
* The number of nodes in the tree is in the range [1, 105].
* `1 <= Node.val <= 9`