合并二叉树-递归
合并二叉树
http://www.nowcoder.com/questionTerminal/7298353c24cc42e3bd5f0e0bd3d1d759
非常简单的代码^_^
解题思路：
- 两个节点的值求和并赋给t1
- 递归合并t1、t2的左右节点。
public TreeNode mergeTrees (TreeNode t1, TreeNode t2) {
if(t1 == null) return t2;
if(t2 == null) return t1;
t1.val += t2.val;
t1.left = mergeTrees(t1.left, t2.left);
t1.right = mergeTrees(t1.right, t2.right);
return t1;
} 
