[617. Merge Two Binary Trees] #leetcode

617_0902.java

class Solution {
    public TreeNode mergeTrees(TreeNode t1, TreeNode t2) {
        if (t1 == null && t2 == null) return null;
        
        TreeNode node = new TreeNode(t1 == null? t2.val : t2 == null? t1.val : t1.val + t2.val);
        node.left = mergeTrees(t1 == null? null : t1.left, t2 == null? null : t2.left);
        node.right = mergeTrees(t1 == null? null : t1.right, t2 == null? null : t2.right);
        
        return node;
    }
}