617. 合并二叉树

做一个递归就行/** * 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 { public TreeNode mergeTrees(TreeNode root1, TreeNode root2) { if (root1 null) return root2; if (root2 null) return root1; root1.val root2.val; root1.left mergeTrees(root1.left, root2.left); root1.right mergeTrees(root1.right, root2.right); return root1; } }