二叉树的递归创建和遍历

/*

author:justinzhang

email:uestczhangchao@gmail.com

time:2012-8-2015:52:27

des.:usingnonrecursivemethodtotraversebinarytree

*/

#include<iostream>

usingnamespacestd;

template<typenameT>classbtree

{

public:

Tdata;

btree*lchild,*rchild;

};

/*createbinarytree,withoneparameter.

thebinarytreeisinputedthroughpreorder,

1

23,isinputas12-1-13-1-1,(-1representnilnode);

*/

btree<double>*create_btr(btree<double>**root)

{

doubledata;

cin>>data;

/*-1.0representthenilnode*/

if(data==-1.0)

{

*root=NULL;

}

else

{

*root=newbtree<double>();

(*root)->data=data;

(*root)->lchild=create_btr(&(*root)->lchild);

(*root)->rchild=create_btr(&(*root)->rchild);

}

return*root;

}

/*createbinarytreewithoutparameter!*/

btree<double>*create_btr()

{

doubledata;

cin>>data;

if(data==-1)

returnNULL;//returnnillnode

else

{

btree<double>*T=newbtree<double>;

T->data=data;

T->lchild=create_btr();

T->rchild=create_btr();

returnT;

}

}

voidpreorder(btree<double>*r)

{

if(r==NULL)

return;

cout<<r->data<<endl;

preorder(r->lchild);

preorder(r->rchild);

}

voidinorder(btree<double>*r)

{

if(NULL==r)

return;

inorder(r->lchild);

cout<<r->data<<endl;

inorder(r->rchild);

}

voidpostorder(btree<double>*r)

{

if(NULL==r)

return;

postorder(r->lchild);

postorder(r->rchild);

cout<<r->data<<endl;

}

intmain()

{

btree<double>*root=NULL;

create_btr(&root);

//btree<double>*T=create_btr();

preorder(root);

inorder(root);

postorder(root);

//inorder(T);

return0;

}

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