按之字形打印数据

 1 class Solution {
 2 public:
 3     vector<vector<int> > Print(TreeNode* pRoot) {
 4         vector<vector<int>> res;
 5         if(pRoot == NULL)
 6             return res;
 7         stack<TreeNode*> num[2];
 8         int flag[2];
 9         int i=0;
10         num[0].push(pRoot);
11        // flag[0]=1;
12         while(!num[0].empty() || !num[1].empty())
13         {
14             vector<int> prin;
15             while(!num[i].empty())
16             {
17                 
18                 prin.push_back(num[i].top()->val);
19                 if(i==1)
20                 {
21                    if(num[i].top()->right)
22                        num[1-i].push(num[i].top()->right);
23                     if(num[i].top()->left)
24                        num[1-i].push(num[i].top()->left);
25                 }
26                 else
27                 {
28                     if(num[i].top()->left)
29                        num[1-i].push(num[i].top()->left);
30                     if(num[i].top()->right)
31                        num[1-i].push(num[i].top()->right);
32                 }
33                num[i].pop();
34                 
35             }
36             res.push_back(prin);
37             i=1-i;
38         }
39         return res;
40     }
41     
42 };