617. 合并二叉树

题目描述

代码

• 按照这样的顺序合并节点
  • root.val = ？
  • root.left = ?
  • root.right = ?

class Solution {
    public TreeNode mergeTrees(TreeNode root1, TreeNode root2) {
        if (root1 == null && root2 == null) {
            return null;
        }
        if (root1 == null || root2 == null) {
            return root1 == null ? root2 : root1;
        }
        root1.val += root2.val;
        root1.left = mergeTrees(root1.left, root2.left);
        root1.right = mergeTrees(root1.right, root2.right);
        return root1;
    }
}