操作给定的二叉树，将其变换为源二叉树的镜像。

/*
struct TreeNode {
int val;
struct TreeNode *left;
struct TreeNode *right;
TreeNode(int x) :
val(x), left(NULL), right(NULL) {
}
};*/
class Solution {
public:
void Mirror(TreeNode *pRoot) {
if(pRoot == nullptr){
return ;
}
if(pRoot->left == nullptr && pRoot->right == nullptr){
return;
}
TreeNode * pTemp =pRoot->left;
pRoot->left = pRoot->right;
pRoot->right = pTemp;
if(pRoot->left){
Mirror(pRoot->left);
}
if(pRoot->right){
Mirror(pRoot->right);
}

}
};