617. Merge Two Binary Trees.cpp

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    TreeNode* mergeTrees(TreeNode* root1, TreeNode* root2) {
       if (root1== NULL)
           return root2;
       if (root2==NULL)
           return root1;
        root1->val+=root2->val;
        root1->left=mergeTrees(root1->left, root2->left);
        root1->right=mergeTrees(root1->right,root2->right);
           return root1;
    }
};
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