1379.find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree.java

/*
 * @lc app=leetcode id=1379 lang=java
 *
 * [1379] Find a Corresponding Node of a Binary Tree in a Clone of That Tree
 *
 * https://leetcode.com/problems/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree/description/
 *
 * algorithms
 * Medium (84.11%)
 * Likes:    65
 * Dislikes: 101
 * Total Accepted:    9.5K
 * Total Submissions: 11.3K
 * Testcase Example:  '[7,4,3,null,null,6,19]\n3'
 *
 * Given two binary trees original and cloned and given a reference to a node
 * target in the original tree.
 * 
 * The cloned tree is a copy of the original tree.
 * 
 * Return a reference to the same node in the cloned tree.
 * 
 * Note that you are not allowed to change any of the two trees or the target
 * node and the answer must be a reference to a node in the cloned tree.
 * 
 * Follow up: Solve the problem if repeated values on the tree are allowed.
 * 
 * 
 * Example 1:
 * 
 * 
 * Input: tree = [7,4,3,null,null,6,19], target = 3
 * Output: 3
 * Explanation: In all examples the original and cloned trees are shown. The
 * target node is a green node from the original tree. The answer is the yellow
 * node from the cloned tree.
 * 
 * 
 * Example 2:
 * 
 * 
 * Input: tree = [7], target =  7
 * Output: 7
 * 
 * 
 * Example 3:
 * 
 * 
 * Input: tree = [8,null,6,null,5,null,4,null,3,null,2,null,1], target = 4
 * Output: 4
 * 
 * 
 * Example 4:
 * 
 * 
 * Input: tree = [1,2,3,4,5,6,7,8,9,10], target = 5
 * Output: 5
 * 
 * 
 * Example 5:
 * 
 * 
 * Input: tree = [1,2,null,3], target = 2
 * Output: 2
 * 
 * 
 * 
 * Constraints:
 * 
 * 
 * The number of nodes in the tree is in the range [1, 10^4].
 * The values of the nodes of the tree are unique.
 * target node is a node from the original tree and is not null.
 * 
 * 
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */

class Solution {
    public final TreeNode getTargetCopy(final TreeNode original, final TreeNode cloned, final TreeNode target) {
        if (original == null) return null;
        if (original == target) return cloned;
        
        TreeNode leftNode = getTargetCopy(original.left, cloned.left, target);
        TreeNode rightNode = getTargetCopy(original.right, cloned.right, target);
        
        if (leftNode == null) return rightNode;
        if (rightNode == null) return leftNode;
        return null;
    }
}
// @lc code=end