刷题——合并二叉树

合并二叉树_牛客题霸_牛客网

方法一：

TreeNode* mergeTrees(TreeNode* t1, TreeNode* t2) {
        // write code here
        if(t1 == NULL) return t2;
        if(t2 == NULL) return t1;
        TreeNode* head= new TreeNode(t1->val + t2->val);
        head->left = mergeTrees(t1->left, t2->left);
        head->right = mergeTrees(t1->right, t2->right);
        return head;
    }

方法二：

TreeNode* mergeTrees(TreeNode* t1, TreeNode* t2) {
        // write code here
        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;
    }