从上往下打印二叉树

题目描述

从上往下打印出二叉树的每个节点，同层节点从左至右打印。

/*
struct TreeNode {
	int val;
	struct TreeNode *left;
	struct TreeNode *right;
	TreeNode(int x) :
			val(x), left(NULL), right(NULL) {
	}
};*/
class Solution {
public:
vector<int> PrintFromTopToBottom(TreeNode* root) {
	vector<int> ans;
	if(!root)
		return ans;

	queue<TreeNode*> temp;
	temp.push(root);
	
	while(!temp.empty())
	{
		TreeNode* cur = temp.front();
		ans.push_back(cur->val);

		temp.pop();

		if(cur->left)
			temp.push(cur->left);
		if(cur->right)
			temp.push(cur->right);
	} 
    return ans;
}
  
};