Merge Two Binary Trees
给两个二叉树, 合并成一个二叉树, 合并的规则是如果一边是null, 就是另一侧是值, 如果两边都不是null就是两个值的和.
/**
* 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 && root2 == null)
return null;
if(root1 == null)
return root2;
if(root2 == null)
return root1;
TreeNode root = new TreeNode((root1 == null ? 0 : root1.val) + (root2 == null ? 0 : root2.val));
root.left = mergeTrees(root1.left, root2.left);
root.right = mergeTrees(root1.right, root2.right);
return root;
}
}