思路：
模拟
解答：
package bupt;import java.util.Scanner;/*
*@author:Totoro
*@createDate:2020年3月18日下午4:16:16
*/
public class 二叉排序树{static point[] tree=new point[105];static int n;public static void main(String[] args){Scanner cin=new Scanner(System.in);int N,x;while(cin.hasNext()){N=cin.nextInt();n=1;x=cin.nextInt();tree[0]=new point(x);System.out.println(-1);while(N--!=1){x=cin.nextInt();insert(x,0);}}}public static void insert(int x,int pos){if(tree[pos].value>x){if(tree[pos].lc==-1){point p=new point(x);tree[pos].lc=n;p.pre=pos;tree[n++]=p;System.out.println(tree[pos].value);}elseinsert(x,tree[pos].lc);}else{if(tree[pos].rc==-1){point p=new point(x);tree[pos].rc=n;p.pre=pos;tree[n++]=p;System.out.println(tree[pos].value);}elseinsert(x,tree[pos].rc);}}public static class point{int pre;int lc,rc;int value;public point(int x){value=x;pre=-1;lc=-1;rc=-1;}}}