Package g1401_1500.s1457_pseudo_palindromic_paths_in_a_binary_tree

Class Solution

  • 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:

    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

    • Constructor Detail

      • Solution

        public Solution()

    • Method Detail

      • pseudoPalindromicPaths

        public int pseudoPalindromicPaths​(TreeNode root)