从上往下打印二叉树

题目描述

解答

vector<int> PrintFromTopToBottom(TreeNode *root) {
vector<int> ret;
if(!root)
return ret;
deque<TreeNode *> queue;
queue.push_back(root);
while(!queue.empty())
{
TreeNode* node  = queue.front();
queue.pop_front();
ret.push_back(node->val);
if(node->left)
queue.push_back(node->left);
if(node->right)
queue.push_back(node->right);
}

return ret;

}