1372_Longest_ZigZag_Path_in_a_Binary_Tree.java

/*
 * 1372. Longest ZigZag Path in a Binary Tree
 * Problem Link: https://leetcode.com/problems/longest-zigzag-path-in-a-binary-tree/
 * Difficulty:   Medium
 * 
 * Solution Created by: Muhammad Khuzaima Umair
 * LeetCode : https://leetcode.com/mkhuzaima/
 * Github   : https://github.com/mkhuzaima
 * LinkedIn : https://www.linkedin.com/in/mkhuzaima/
 */

class Solution {
    int maxLength = 0;
    public int longestZigZag(TreeNode root) {
        dfs(root.left, false, 1);
        dfs(root.right, true, 1);
        return maxLength;
    }

    private void dfs(TreeNode root, boolean toLeft, int sum) {
        if (root == null) {
            return;
        }


        maxLength = Math.max(maxLength, sum);
        if (toLeft) {
            dfs(root.left, false, sum +1);
            dfs(root.right, true, 1);
        }
        else {
            dfs(root.right, true, sum +1);
            dfs(root.left, false, 1);
        }
        
    }
}