Package g1401_1500.s1457_pseudo_palindromic_paths_in_a_binary_tree

Class Solution

java.lang.Object
g1401_1500.s1457_pseudo_palindromic_paths_in_a_binary_tree.Solution
public class Solution extends Object
1457 - Pseudo-Palindromic Paths in a Binary Tree.<p>Medium</p> <p>Given a binary tree where node values are digits from 1 to 9. A path in the binary tree is said to be <strong>pseudo-palindromic</strong> if at least one permutation of the node values in the path is a palindrome.</p> <p><em>Return the number of <strong>pseudo-palindromic</strong> paths going from the root node to leaf nodes.</em></p> <p><strong>Example 1:</strong></p> <p><img src="https://assets.leetcode.com/uploads/2020/05/06/palindromic_paths_1.png" alt="" /></p> <p><strong>Input:</strong> root = [2,3,1,3,1,null,1]</p> <p><strong>Output:</strong> 2</p> <p><strong>Explanation:</strong> 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).</p> <p><strong>Example 2:</strong></p> <p><strong><img src="https://assets.leetcode.com/uploads/2020/05/07/palindromic_paths_2.png" alt="" /></strong></p> <p><strong>Input:</strong> root = [2,1,1,1,3,null,null,null,null,null,1]</p> <p><strong>Output:</strong> 1</p> <p><strong>Explanation:</strong> 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).</p> <p><strong>Example 3:</strong></p> <p><strong>Input:</strong> root = [9]</p> <p><strong>Output:</strong> 1</p> <p><strong>Constraints:</strong></p> <ul> <li>The number of nodes in the tree is in the range <code>[1, 10<sup>5</sup>]</code>.</li> <li><code>1 <= Node.val <= 9</code></li> </ul>

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • pseudoPalindromicPaths

      public int pseudoPalindromicPaths(TreeNode root)