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LongestZigzagPath.java
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/*https://leetcode.com/problems/longest-zigzag-path-in-a-binary-tree/*/
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
int max;
public int longestZigZag(TreeNode root) {
max = 0;
recur(root,'\0');
return max;
}
private int recur(TreeNode root, char dir)
{
if (root == null) return 0;
int left = recur(root.left, 'l');
int right = recur(root.right, 'r');
int curr = 0;
if (dir == 'l') curr = right+1;
else if (dir == 'r') curr = left+1;
if (curr > max)
max = curr;
return curr;
}
}