模板_建立二叉搜索树_递推

//
#include<bits/stdc++.h>
using namespace std;
#define T int            // 随时修改数据类型

const int N=111;
T ans[N];
int pos;

struct node
{
    T data;
    node *x,*y;
    node( T in=0,node *xx=NULL,node *yy=NULL ):data(in),x(xx),y(yy) {} 
};

void new_tree( int n,node* &root )
{
    while( n-- )
    {
        T data; cin>>data;
        node *tt=new node( data );

        if( root==NULL ) { root=tt; continue; }

        node *rp=root;				// 移动指针 
        while( 1 )
        {
            if( data < rp->data )	// left
            {
                if( rp->x ) rp=rp->x;
                else { rp->x=tt; break; }  
            }
            else 					// right
            {
                if( rp->y ) rp=rp->y;
                else { rp->y=tt; break; }
            }
        }
    }
}

void BB( node *root )
{
    if( root==NULL ) return ;
    BB( root->x );
    ans[pos++]=root->data;
    BB( root->y );
}

void delete_tree( node *root )
{
    if( root==NULL ) return ;
    delete_tree( root->x );
    delete_tree( root->y );
    delete root;
}

int main()
{
    int n,i;
    while( cin>>n )
    {
        node *root=NULL;
        new_tree( n,root );
        
        pos=0; BB( root );
        for( i=0;i<pos;i++ )
        {
            if( i ) cout<<" ";
            cout<<ans[i];
        }
        cout<<endl;

        delete_tree( root );
    }
    return 0;
}