剑指Offer系列-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，该函数输出它的镜像。二叉树的结点定义如下：

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

思路：

代码：// 递归实现
void MirrorRecursively(BinaryTreeNode *pNode)
{
if((pNode == NULL) || (pNode->m_pLeft == NULL && pNode->m_pRight == NULL))
return;

BinaryTreeNode *pTemp = pNode->m_pLeft;
pNode->m_pLeft = pNode->m_pRight;
pNode->m_pRight = pTemp;

if(pNode->m_pLeft)
MirrorRecursively(pNode->m_pLeft);

if(pNode->m_pRight)
MirrorRecursively(pNode->m_pRight);
}

// 非递归实现
void MirrorIteratively(BinaryTreeNode* pRoot)
{
if(pRoot == NULL)
return;

std::stack<BinaryTreeNode*> stackTreeNode;
stackTreeNode.push(pRoot);

while(stackTreeNode.size() > 0)
{
BinaryTreeNode *pNode = stackTreeNode.top();
stackTreeNode.pop();

BinaryTreeNode *pTemp = pNode->m_pLeft;
pNode->m_pLeft = pNode->m_pRight;
pNode->m_pRight = pTemp;

if(pNode->m_pLeft)
stackTreeNode.push(pNode->m_pLeft);

if(pNode->m_pRight)
stackTreeNode.push(pNode->m_pRight);
}
}