剑指Offer 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) {

    }
};

class Solution {
public:
    vector<int> PrintFromTopToBottom(TreeNode* root) {
        queue<TreeNode*> que;

        vector<int> vec;
        if(root == NULL) return vec;
        que.push(root);

        while(!que.empty()) {
            TreeNode* tr;
            tr = que.front();
            que.pop();

            if(tr == NULL) continue;

            vec.push_back(tr->val);
            que.push(tr->left);
            que.push(tr->right);
        }
        return vec;
    }
};