剑指offer——面试题23：从上往下打印二叉树

剑指offer——面试题23：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) {
vector<int> res;
if(root == NULL)
return res;
deque<TreeNode*> deque;
deque.push_back(root);
while(!deque.empty()){
int a = deque.front()->val;
res.push_back(a);
if(deque.front()->left != NULL)
deque.push_back(deque.front()->left);
if(deque.front()->right != NULL)
deque.push_back(deque.front()->right);
deque.pop_front();
}
return res;
}
};