判断平衡二叉树

先上代码：

#include<iostream>
using namespace std;

struct BiNode{
	char date;
	BiNode *lchild,*rchild;
};
class BiTree{
private:
	BiNode *root;
public:
	BiTree(){root=Creat(root);}
	~BiTree(){Release(root);}
	void PreOrder(){PreOrder(root);}
	void InOrder(){InOrder(root);}
	void PostOrder(){PostOrder(root);}
	int Depth(){return Depth(root);}
	int Isblancedtree(){return Isblancedtree(root);}
private:
	BiNode *Creat(BiNode *bt);
	void Release(BiNode *bt);
	void PreOrder(BiNode *bt);
	void InOrder(BiNode *bt);
	void PostOrder(BiNode *bt);
	int Depth(BiNode *bt);
	int Isblancedtree(BiNode *bt);
};

BiNode* BiTree::Creat(BiNode *bt){
	char ch;
	cin>>ch;
	if(ch=='#')
		bt=NULL;
	else{
		bt=new BiNode;
		bt->date=ch;
		bt->lchild=Creat(bt->lchild);
		bt->rchild=Creat(bt->rchild);
	}
	return bt;
}
void BiTree::Release(BiNode *bt){
	cout << "~TreeNode()" << endl;  
	if(bt->lchild!=NULL){  
		delete bt->lchild; //递归析构左子树  
	}  
    if(bt->rchild!=NULL){  
        delete bt->rchild;//递归析构右子树  
    }  
}
void BiTree::PreOrder(BiNode *bt){
	if(bt==NULL)
		return;
	else{
		cout<<bt->date;
		PreOrder(bt->lchild);
		PreOrder(bt->rchild);
	}
}
void BiTree::InOrder(BiNode *bt){
	if(bt==NULL)
		return;
	else{	
		InOrder(bt->lchild);
		cout<<bt->date;
		InOrder(bt->rchild);
	}
}
void BiTree::PostOrder(BiNode *bt){
	if(bt==NULL)
		return;
	else{	
		PostOrder(bt->lchild);
		PostOrder(bt->rchild);
		cout<<bt->date;
	}
}
int BiTree::Depth(BiNode *bt){
	if(bt==NULL)
		return 0;
	else
	{
		int a=Depth(bt->lchild);
		int b=Depth(bt->rchild);
		return (a>b)? (a+1):(b+1);
	}
}
int BiTree::Isblancedtree(BiNode *bt)
{
	if(bt==NULL)
		return 1;
	int left=Depth(bt->lchild);
	int right=Depth(bt->rchild);
	int gap=left-right;
	if(gap>1||gap<-1)
		return 0;
	return Isblancedtree(bt->lchild)&&Isblancedtree(bt->rchild);
}
int main()
{
	cout<<"请输入二叉树的字符串:";
	BiTree Tree;
	cout<<"前序遍历为：";
	Tree.PreOrder();
	cout<<endl;
	cout<<"二叉树的深度：";
	cout<<Tree.Depth()<<endl;
	if(Tree.Isblancedtree()!=0)
		cout<<"是平衡二叉树"<<endl;
	else
		cout<<"不是平衡二叉树"<<endl;
	return 0;
}

再看测试数据：

请输入二叉树的字符串:6421##3##5##87##9##
前序遍历为：642135879
二叉树的深度：4
是平衡二叉树
~TreeNode()
Press any key to continue

判断平衡二叉树先构建二叉树：

struct BiNode{
	char date;
	BiNode *lchild,*rchild;
};
class BiTree{
private:
	BiNode *root;
public:
	BiTree(){root=Creat(root);}
	~BiTree(){Release(root);}
	void PreOrder(){PreOrder(root);}
	void InOrder(){InOrder(root);}
	void PostOrder(){PostOrder(root);}
	int Depth(){return Depth(root);}
	int Isblancedtree(){return Isblancedtree(root);}
private:
	BiNode *Creat(BiNode *bt);
	void Release(BiNode *bt);
	void PreOrder(BiNode *bt);
	void InOrder(BiNode *bt);
	void PostOrder(BiNode *bt);
	int Depth(BiNode *bt);
	int Isblancedtree(BiNode *bt);
};

关键是：

int BiTree::Depth(BiNode *bt){
	if(bt==NULL)
		return 0;
	else
	{
		int a=Depth(bt->lchild);
		int b=Depth(bt->rchild);
		return (a>b)? (a+1):(b+1);
	}
}
int BiTree::Isblancedtree(BiNode *bt)
{
	if(bt==NULL)
		return 1;
	int left=Depth(bt->lchild);
	int right=Depth(bt->rchild);
	int gap=left-right;
	if(gap>1||gap<-1)
		return 0;
	return Isblancedtree(bt->lchild)&&Isblancedtree(bt->rchild);
}