C++实现二叉树的基本操作：建立、遍历、计算深度、节点数、叶子数等

题意：

代码实现：

#include<iostream>
#include<queue>
#include<stack>

using namespace std;

//二叉树节点
struct BinaryTreeNode
{
char data;
BinaryTreeNode* leftChild;
BinaryTreeNode* rightChild;
};
//堆栈节点，用于深度遍历
struct stackNode
{
BinaryTreeNode* ptr;
char tag;//tag=0标志进入左子树，tag=1标志进入右子树
};

class BinaryTree //二叉树的类
{
public:
//根据完全前序遍历创建二叉树
void createBinaryTree(BinaryTreeNode* &root)
{
root=new BinaryTreeNode();
char newData;
cin>>newData;
if(newData=='#')
{
root=NULL;
}
else
{
root->data=newData;
createBinaryTree(root->leftChild);
createBinaryTree(root->rightChild);
}
}
//递归实现前序遍历
void preTraversal(BinaryTreeNode* root)
{
if(root!=NULL)
{
cout<<root->data<<" ";
preTraversal(root->leftChild);
preTraversal(root->rightChild);
}
}

//递归实现后续遍历
void lastTraversal(BinaryTreeNode* root)
{
if(root!=NULL)
{
lastTraversal(root->leftChild);
lastTraversal(root->rightChild);
cout<<root->data<<" ";
}
}

//非递归实现中序遍历
void mid(BinaryTreeNode* root)
{
stack<BinaryTreeNode*> S;
BinaryTreeNode* p=root;
do
{
while(p!=NULL)
{
S.push(p);
p=p->leftChild;
}
if(!S.empty())
{
p=S.top();
cout<<p->data<<" ";
S.pop();
p=p->rightChild;
}
}
while(p!=NULL||!S.empty());
}

//计算节点总数
int nodeCount(BinaryTreeNode* &root)
{
if(root==NULL)
{
return 0;
}
else
{
return nodeCount(root->leftChild)+nodeCount(root->rightChild)+1;
}
}
//计算二叉树的高度
int treeHight(BinaryTreeNode* &root)
{
if(root==NULL)
{
return 0;
}
else
{
int LH=treeHight(root->leftChild);
int RH=treeHight(root->rightChild);
return LH > RH ? LH+1 : RH+1;
}
}
//计算二叉树的叶子个数
int getLeavesCount(BinaryTreeNode* &root)
{
if(root==NULL)
{
return 0;
}
else if (root->leftChild == NULL && root->rightChild == NULL)
{
return 1;
}
else
{
int leftLeavesCount = getLeavesCount(root->leftChild);
int rightLeavesCount = getLeavesCount(root->rightChild);
return leftLeavesCount + rightLeavesCount;
}
}
//查找值=x的节点个数
int findNode(BinaryTreeNode* &root,char x,int coun)
{

if(root!=NULL)
{
if(root->data==x) coun++;
findNode(root->leftChild,x,coun);
findNode(root->rightChild,x,coun);
}
return coun;
}
//以缩格文本形式输出所有节点
void outputNode(BinaryTreeNode* &root,int x)
{
if(root!=NULL)
{
for(int i=0;i<x;i++) cout<<" ";
cout<<root->data<<endl;
x=x+2;
outputNode(root->leftChild,x);
outputNode(root->rightChild,x);
}

}

};

int main()
{
BinaryTree tree;
BinaryTreeNode* treeRoot;
char func;
while(cin>>func){
if(func=='C')
{
tree.createBinaryTree(treeRoot);
cout<<"Created success!";
}
if(func=='1') {cout<<"Preorder is:";tree.preTraversal(treeRoot);cout<<".";}
if(func=='2') {cout<<"Inorder is:";tree.mid(treeRoot);cout<<".";}
if(func=='3') {cout<<"Postorder is:";tree.lastTraversal(treeRoot);cout<<".";}
if(func=='N') cout<<"Nodes="<<tree.nodeCount(treeRoot)<<".";
if(func=='H') cout<<"Height="<<tree.treeHight(treeRoot)<<".";
if(func=='L') cout<<"Leaf="<<tree.getLeavesCount(treeRoot)<<".";
if(func=='F')
{
char x;
cin>>x;
cout<<"The count of "<<x<<" is "<<tree.findNode(treeRoot,x,0)<<".";
}
if(func=='P')
{
cout<<"The tree is:"<<endl;
tree.outputNode(treeRoot,0);
}
cout<<endl;
}

return 0;
}

PS：有时间再补充注意点吧