翻轉(zhuǎn)一棵二叉樹

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/**
 * Definition of TreeNode:
 * class TreeNode {
 * public:
 *     int val;
 *     TreeNode *left, *right;
 *     TreeNode(int val) {
 *         this->val = val;
 *         this->left = this->right = NULL;
 *     }
 * }
 */
class Solution {
public:
    /**
     * @param root: a TreeNode, the root of the binary tree
     * @return: nothing
     */
    void invertBinaryTree(TreeNode *root) {
        // write your code here
        if(root!=NULL){
            TreeNode * temp=root->left;
            root->left=root->right;
            root->right=temp;
            invertBinaryTree(root->right);
            invertBinaryTree(root->left);
        }
        return ;
    }
};