操作给定的二叉树,将其变换为源二叉树的镜像。
递归思想。
代码:
#include<iostream>
#include <vector>
#include <queue>
using namespace std;
struct TreeNode {
int val;
struct TreeNode *left;
struct TreeNode *right;
TreeNode(int x) :
val(x), left(NULL), right(NULL) {
}
};
void Mirror(TreeNode *pRoot) //核心代码
{
if(pRoot==NULL) //空树
return;
if(pRoot->left==NULL&&pRoot->right==NULL) //只有一个结点的二叉树
return;
TreeNode* pTemp=pRoot->left; //创建一个临时结点指针,用于交换左右子节点
pRoot->left=pRoot->right;
pRoot->right=pTemp; //交换根节点的左右结点
if(pRoot->left!=NULL)
Mirror(pRoot->left);
if(pRoot->right!=NULL)
Mirror(pRoot->right);
}
class BinTree
{
public:
TreeNode *root;
TreeNode* CreateTree();
void preOrder(TreeNode *r);//递归实现先序遍历
void InOrder(TreeNode *r);//递归实现中序遍历
void PostOrder(TreeNode *r);//递归实现后续遍历
};
TreeNode* BinTree::CreateTree()//创建一棵二叉树
{
TreeNode *p1=new TreeNode(1);
TreeNode *p2=new TreeNode(2);
TreeNode *p3=new TreeNode(3);
TreeNode *p4=new TreeNode(4);
TreeNode *p5=new TreeNode(5);
TreeNode *p6=new TreeNode(6);
TreeNode *p7=new TreeNode(7);
TreeNode *p8=new TreeNode(8);
TreeNode *p9=new TreeNode(9);
p1->left=p2;
p1->right=p3;
p2->left=p4;
p2->right=p5;
p5->left=p6;
p3->left=p7;
p3->right=p8;
p8->right=p9;
root=p1;
return root;
}
void Print(vector<int> &myarray)
{
int num=myarray.size();
for(int i=0; i<num;i++)
cout<<myarray[i]<<" ";
cout<<endl;
return;
}
vector<int> PrintFromTopToBottom(TreeNode* root)
{
vector<int> res;
if(root==NULL)
return res;
queue<TreeNode*> q;
q.push(root);
while(!q.empty())
{
res.push_back(q.front()->val);
if(q.front()->left!=NULL)
q.push(q.front()->left);
if(q.front()->right!=NULL)
q.push(q.front()->right);
q.pop();
}
return res;
}
int main()
{
BinTree t;
TreeNode* root=t.CreateTree();//创建二叉树
vector<int>vec= PrintFromTopToBottom( root );
Print(vec);
Mirror(root);
vector<int>vec2= PrintFromTopToBottom( root );
Print(vec2);
return 0;
}