题解 | #从上往下打印二叉树#

/*
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) {
		queue<TreeNode*> queue;
		vector<int> res;
		if (!root) return res;
		queue.push(root);
		while (!queue.empty()){
			res.push_back(queue.front()->val);
			if (queue.front()->left) queue.push(queue.front()->left);
			if (queue.front()->right) queue.push(queue.front()->right);
			queue.pop();
		}
		return res;
    }
};