919. 完全二叉树插入器

原题链接：919. 完全二叉树插入器

 

solution:
        

/**
 * 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 CBTInserter {
public:
    TreeNode *R;
    vector<TreeNode *> h;
    CBTInserter(TreeNode* root) {   //建立完全二叉树
        h.resize(1);
        R = root;
        queue<TreeNode*> q;
        q.push(root);
        while (q.size()) {
            auto t = q.front();
            q.pop();
            h.push_back(t);
            if (t->left) q.push(t->left);
            if (t->right) q.push(t->right);
        }
    }   
    int insert(int val) {
        auto t = new TreeNode(val);
        h.push_back(t);
        int k = h.size() - 1;   //结点在堆中的位置
        int p = k / 2;
        if(k == 2 * p) h[p]->left = t;
        else h[p]->right = t;
        return h[p]->val;
    }
    
    TreeNode* get_root() {
        return R;
    }
};

/**
 * Your CBTInserter object will be instantiated and called as such:
 * CBTInserter* obj = new CBTInserter(root);
 * int param_1 = obj->insert(val);
 * TreeNode* param_2 = obj->get_root();
 */