这个人懒死了不想写解释

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
     
       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;        }    }}