226.翻转二叉树

翻转一棵二叉树。

示例：

输入：

     4
   /   \
  2     7
 / \   / \
1   3 6   9

输出：

     4
   /   \
  7     2
 / \   / \
9   6 3   1

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
struct TreeNode* invertTree(struct TreeNode* root) {
    postorder(root);
    return root;
}
void postorder(struct TreeNode* Ptr){
    if(Ptr){
        postorder(Ptr->left);
        postorder(Ptr->right);
        struct TreeNode* n=NULL;
        n=Ptr->left;
        Ptr->left=Ptr->right;
        Ptr->right=n;
    }
}