剑指offer 面试题19：二叉树的镜像

题目：
请完成一个函数，输入一个二叉树，输出它的镜像

struct binaryTreeNode {
    int                        m_nValue;
    binaryTreeNode*  m_pLeft;
    binaryTreeNode*  m_pRight;
};

解法：

void mirrorBinTree(binaryTreeNode* pRoot) {
    if (pRoot == 0 || (pRoot->m_pLeft == 0 && pRoot->m_pRight == 0)) {
        return;
    }
    binaryTreeNode*  tmp  =  pRoot->m_pLeft;
    pRoot->m_pLeft  =  pRoot->m_pRight;
    pRoot->m_pRight  =  tmp;

    if (pRoot->m_pLeft) {
        mirrorBinTree(pRoot->m_pLeft);
    }
    if (pRoot->m_pRight) {
        mirrorBinTree(pRoot->m_pRight);
    }
}