LeetCode: Flatten Binary Tree to Linked List

忘记加tmp->left = NULL了，少数次改

 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     void flatten(TreeNode *root) {
13         // Start typing your C/C++ solution below
14         // DO NOT write int main() function
15         stack<TreeNode *> S;
16         if (!root) return;
17         TreeNode *tmp = root;
18         while (tmp) {
19             if (tmp->right) S.push(tmp->right);
20             if (tmp->left) {
21                 tmp->right = tmp->left;
22                 tmp->left = NULL;
23                 tmp = tmp->right;
24             }
25             else {
26                 if (!S.empty()) {
27                     tmp->right = S.top();
28                     tmp = tmp->right;
29                     S.pop();
30                 }
31                 else break;
32             }
33         }
34         return;
35     }
36 };

贴上另外一段

 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     void flatten(TreeNode *root) {
13         // Start typing your C/C++ solution below
14         // DO NOT write int main() function
15         stack<TreeNode*> S;
16         while (root) {
17             if (root->left) {
18                 if (root->right) S.push(root->right);
19                 root->right = root->left;
20                 root->left = NULL;
21             }
22             else if (!root->right && !S.empty()) {
23                 root->right = S.top();
24                 S.pop();
25             }
26             root = root->right;
27         }
28     }
29 };

 1 /**
 2  * Definition for a binary tree node.
 3  * public class TreeNode {
 4  *     public int val;
 5  *     public TreeNode left;
 6  *     public TreeNode right;
 7  *     public TreeNode(int x) { val = x; }
 8  * }
 9  */
10 public class Solution {
11     public void Flatten(TreeNode root) {
12         Stack<TreeNode> S = new Stack<TreeNode>();
13         while (root != null) {
14             if (root.left != null) {
15                 if (root.right != null) S.Push(root.right);
16                 root.right = root.left;
17                 root.left = null;
18             }
19             else if (root.right == null && S.Count != 0) {
20                 root.right = S.Peek();
21                 S.Pop();
22             }
23             root = root.right;
24         }
25     }
26 }

View Code

Java

 1 /**
 2  * Definition for a binary tree node.
 3  * public class TreeNode {
 4  *     int val;
 5  *     TreeNode left;
 6  *     TreeNode right;
 7  *     TreeNode(int x) { val = x; }
 8  * }
 9  */
10 public class Solution {
11     public void flatten(TreeNode root) {
12         Stack<TreeNode> st = new Stack<TreeNode>();
13         if (root == null) return;
14         while (root != null)
15         {
16             if (root.left != null)
17             {
18                 if (root.right != null) st.push(root.right);
19                 root.right = root.left;
20                 root.left = null;
21                 root = root.right;
22             }
23             else 
24             {
25                 if (root.right == null && st.empty() == false)
26                 {
27                     root.right = st.peek();
28                     st.pop();
29                 }
30                 root = root.right;
31             }
32         }
33     }
34 }

posted @ 2013-03-21 12:21 ying_vincent 阅读(145) 评论(0) 收藏举报

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