Given two binary trees and imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are not. You need to merge them into a new binary tree. The merge rule is that if two nodes overlap, the

test.cpp

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    TreeNode* mergeTrees(TreeNode* t1, TreeNode* t2) {
        if(t1 && t2){
            TreeNode *root = new TreeNode(t1->val + t2->val);
            root->left = mergeTrees(t1->left,t2->left);
            root->right = mergeTrees(t1->right,t2->right);
            return root;
        }
        else {
            return t1 ? t1 : t2;
        }
    }
};