Leetcode fusionar árbol binario

Leetcode fusionar árbol binario

class Solution {
    
    
    public TreeNode mergeTrees_1(TreeNode t1, TreeNode t2) {
    
    
        if (t1 == null) {
    
    
            return t2;
        }
        if (t2 == null) {
    
    
            return t1;
        }
        // 先合并根节点
        t1.val += t2.val;
        // 再递归合并左右子树
        t1.left = mergeTrees(t1.left, t2.left);
        t1.right = mergeTrees(t1.right, t2.right);
        return t1;
    }

    /**
     * 不修改原二叉树的解法
     */
    public TreeNode mergeTrees(TreeNode t1, TreeNode t2) {
    
    
        if (t1 == null && t2 == null) {
    
    
            return null;
        }
        // 先合并根节点
        TreeNode root = new TreeNode((t1 == null ? 0 : t1.val) + (t2 == null ? 0 : t2.val));
        // 再递归合并左右子树
        root.left = mergeTrees(t1 == null ? null : t1.left, t2 == null ? null : t2.left);
        root.right = mergeTrees(t1 == null ? null : t1.right, t2 == null ? null : t2.right);
        return root;
    }
}