把二叉树打印成多行

//与按之字形打印二叉树题目相同，应用队列实现二叉树的打印

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};
*/
class Solution {
public:
        vector<vector<int> > Print(TreeNode* pRoot) {
            vector<vector<int>> ans;
            if(!pRoot) return ans;
            queue<TreeNode*> q;
            q.push(pRoot);
            while(!q.empty())
            {
                vector<int> tmp;
                int n = q.size();
                for(int i =0;i<n;i++)
                {
                    TreeNode* node = q.front();
                    q.pop();
                    tmp.push_back(node->val);
                    if(node->left) q.push(node->left);
                    if(node->right) q.push(node->right);
                }
                ans.push_back(tmp);
            }
            return ans;
        }
};