LeetCode Binary Tree Zigzag Level Order Traversal

 //应该用两个栈  16ms
 1 /**
 2  * Definition for binary tree
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     vector<vector<int> > zigzagLevelOrder(TreeNode *root) {
13         // Start typing your C/C++ solution below
14         // DO NOT write int main() function
15         vector<int> v;
16         vector<vector<int> > re;
17         stack<TreeNode >s;
18         deque<TreeNode >q;
19         TreeNode t(0);
20         if(root==NULL)
21         {
22             return re;
23         }
24         q.push_back(*root);
25         while(!q.empty())
26         {
27             v.clear();
28             while(!q.empty())
29             {
30                 t=q.front();
31                 v.push_back(t.val);
32                 q.pop_front();
33                 
34                 if(t.left)
35                     s.push(*(t.left));
36                 if(t.right)
37                     s.push(*(t.right));
38                 
39             }
40             re.push_back(v);
41             v.clear();
42             while(!s.empty())
43             {
44                 t=s.top();
45                 v.push_back(t.val);
46                 s.pop();               
47                 
48                 if(t.right)
49                     q.push_front(*(t.right));
50                 if(t.left)
51                     q.push_front(*(t.left));
52                 
53             }
54             if(v.size())
55                 re.push_back(v);
56             v.clear();
57         }
58         return re;
59     }
60     
61     
62     
63     
64     
65     
66     
67     
68     
69 };