Binary Tree Preorder Traversal

 

 1 /**
 2  * Definition for a binary tree node.
 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<int> preorderTraversal(TreeNode* root) {
13                vector<int> res;
14                if(root == NULL)
15                       return res;
16                stack<TreeNode*> node;
17                node.push(root);
18                TreeNode *p, *cur;
19                p = root;
20                res.push_back(p->val);
21                while(!node.empty())
22                {
23                       while(p->left != NULL)
24                       {
25                             p = p->left;
26                             res.push_back(p->val);
27                             node.push(p);
28                       }
29                       cur = node.top();
30                       node.pop();
31                       if(cur->right != NULL)
32                       {
33                             p = cur->right;
34                             res.push_back(p->val);
35                             node.push(p);
36                       }
37                }
38                return res;
39     }
40 };

 

posted on 2016-05-23 10:37  RenewDo  阅读(102)  评论(0)    收藏  举报

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