LeetCode617合并二叉树(递归)

题目

去hxd寝室溜达非得让我做下这题 卡了一会做出来了让他心态崩了hhh
以root1为答案树进行返回

    public TreeNode mergeTrees(TreeNode root1, TreeNode root2) {
    
    
        if (root1 == null) return root2;
        if (root2 == null) return root1;
        root1.val = root1.val + root2.val;//加和
        root1.left = mergeTrees(root1.left,root2.left);//向左递归
        root1.right = mergeTrees(root1.right,root2.right);//向右递归
        return root1;
    }