二叉树的构建和层级打印

class TreeNode {
  public:
     int val;
     TreeNode *left;
     TreeNode *right;
     TreeNode():val(-1),left(NULL),right(NULL) {}
     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 };

class Tree {
  public:
    TreeNode* nodesArray;
    int total_count;
    Tree(int arr[], int count) : total_count(count) {
        nodesArray=new TreeNode[count];
        for (int i=0;i<count;i++)
            nodesArray[i].val=arr[i];
        for (int k=1;k<count;k++) {
            if (nodesArray[k].val==-1)//should be empty child
                continue;
            if (k%2==0)
                nodesArray[k/2-1].right=&nodesArray[k];
            else
                nodesArray[k/2].left=&nodesArray[k];
        }
    }
    ~Tree() {
        delete[] nodesArray;
    }
    TreeNode* getRoot() {
        return &nodesArray[0];
    }
};


void print(TreeNode* root) {
    if (!root)
        return;
    queue<TreeNode*> buffer;
    buffer.push(root);
    int current_level_count=1, next_level_count=0;
    while (!buffer.empty()) {
        TreeNode* current=buffer.front();
        buffer.pop();
        if (current)
            cout << current->val << ‘ ‘;
        else
            cout << "null ";
        --current_level_count;
        /*
        if (current->left) {
            buffer.push(current->left);
            ++next_level_count;
        }
        if (current->right) {
            buffer.push(current->right);
            ++next_level_count;
        }*/ //try to display the null child.
        if (current) {
            buffer.push(current->left);
            buffer.push(current->right);
            next_level_count+=2;
        }
        if (current_level_count==0) {
            cout << endl;
            current_level_count=next_level_count;
            next_level_count=0;
        }
    }
}