1 void printNLevel(TreeNode *root, int n) 2 { 3     if (root == NULL) 4     { 5         return ; 6     } 7  8     if (n == 1) 9     {10         cout << root->data << endl;11     }12     else13     {14         printNLevel(root->left, n-1);15         printNLevel(root->right, n-1);16     }17 }  

 1 void TransLevel2(Node* root,int level) 2 { 3     if(root == NULL) 4         return ; 5     else 6     { 7         int count_levels,count_nodes,level_nodes; 8         Node* tmp; 9         Queue<Node*> queue;10         queue.EnQueue(root);11         12         count_levels=1;13 14         while(!queue.IsEmpty())15         {16             if(count_levels == level)17                 break;18 19             count_nodes = 0;20            21             level_nodes = queue.Size();22             23             while(count_nodes < level_nodes)24             {25                tmp = queue.DeQueue();26 27                if(tmp->left != NULL)28                     queue.EnQueue(tmp->left);29 30                if(tmp->right != NULL)31                     queue.EnQueue(tmp->right);32 33                count_nodes++;34             }35 36             count_levels++;37         }38 39         PrintQueue(queue);40     }41 }