Invert Binary Tree

Description：

Invert a binary tree.

     4

   /   \

  2     7

 / \   / \

1   3 6   9

to

     4

   /   \

  7     2

 / \   / \

9   6 3   1

Code:

 1  TreeNode* invertTree(TreeNode* root) {

 2         if (root==NULL || ( root->left == 0 && root->right == 0))

 3             return root;

 4             

 5         if ( root->left && root->right )

 6         {

 7             TreeNode* temp = root->left;

 8             root->left = root->right;

 9             root->right = temp;

10         }

11         else if ( root->left == NULL)

12         {

13             root->left = root->right;

14             root->right = NULL;

15         }

16         else

17         {

18             root->right = root->left;

19             root->left = NULL;

20         }

21         root->left = invertTree(root->left);

22         root->right = invertTree(root->right);

23         return root;

24     }

总结：对题目没有理解清楚，所以不能独立完成