镜像数

struct BinaryTreeNode {
    int val;
    BinaryTreeNode* left;
    BinaryTreeNode* right;
};

void mirrorRecursively(BinaryTreeNode* pNode) {
    if (pNode->left == NULL || pNode->right == NULL) {
        return;
    }
    BinaryTreeNode* temp = pNode->left;
    pNode->left = pNode->right;
    pNode->right = temp;

    mirrorRecursively(pNode->left);
    mirrorRecursively(pNode->right);
}