剑指offer-二叉树镜像

class Solution {
public:
    
    // 采用层次遍历比较麻烦，BFS+递归
    TreeNode* Mirror(TreeNode* pRoot) {
        if(pRoot==nullptr){
            return nullptr;
        }
        TreeNode* tmp=pRoot->left;
        pRoot->left=pRoot->right;
        pRoot->right=tmp;
        Mirror(pRoot->right);
        Mirror(pRoot->left);
        return pRoot;
    }
};