993. Cousins in Binary Tree

/*
In a binary tree, the root node is at depth 0, and children of each depth k node are at depth k+1.

Two nodes of a binary tree are cousins if they have the same depth, but have different parents.

We are given the root of a binary tree with unique values, and the values x and y of two different nodes in the tree.

Return true if and only if the nodes corresponding to the values x and y are cousins.

Example:

     6
   /   \
  3     5
 / \   / \
7   8 1   3

Say two node be 7 and 1, result is TRUE.
Say two nodes are 3 and 5, result is FALSE.
Say two nodes are 7 and 5, result is FALSE.
*/


/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
 
class Solution {
    public int x_level;
    public TreeNode x_parent;
    public int y_level;
    public TreeNode y_parent;
    
    public boolean isCousins(TreeNode root, int x, int y) {
        search(root, x, y, 0, null);
        
        return x_level == y_level && x_parent != y_parent;
    }
    
    public void search(TreeNode root, int x, int y, int level, TreeNode parent)
    {
        if(root== null) return ;
        if(root.val == x)
        {
            x_level = level;
            x_parent = parent;
        }
        if(root.val == y)
        {
            y_level = level;
            y_parent = parent;
        }
        search(root.left,x,y,level+1,root);
        search(root.right,x,y,level+1,root);
    }
}