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/*struct TreeNode {	int val;	struct TreeNode *left;	struct TreeNode *right;	TreeNode(int x) :			val(x), left(NULL), right(NULL) {	}};*/class Solution {
   public:    vector
   
     PrintFromTopToBottom(TreeNode* root) {
           vector
    
     ret;        if (!root) return ret;        queue
     
       q;        q.push(root);                while(!q.empty())        {
               int s = q.size();            while(s--)            {
                   TreeNode *node = q.front();                q.pop();                ret.push_back(node->val);                                if(node->left) q.push(node->left);                if(node->right) q.push(node->right);            }        }        return ret;    }};
     
    
   

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