//根據先序遍歷結果和中序遍歷結果確定唯一的二叉樹，根據中序遍歷結果和後序遍歷結果確定唯一的二叉樹
import java.util.*;
public class Rebuild_Tree {
    public static void main(String args[]){
        int pre[]=new int[]{18,11,17,10};
        int in[]=new int[]{18,11,17,10};
        int post[]=new int[]{10,17,11,18};
        //根據先序和中序構造樹，並分別打印出先序、中序、後序和層次遍歷的結果
        Tree root1=f_pre_in(pre,in);
        System.out.println("先序：");
        f_pre(root1);
        System.out.println();
        System.out.println("中序：");
        f_in(root1);
        System.out.println();
        System.out.println("後序：");
        f_post(root1);
        System.out.println();
        System.out.println("層次遍歷：");
        f_ceng(root1);
        System.out.println();
        //根據中序和後序構造樹，並分別打印出先序、中序、後序和層次遍歷的結果
        Tree root2=f_in_post(in,post);
        System.out.println("先序：");
        f_pre(root2);
        System.out.println();
        System.out.println("中序：");
        f_in(root2);
        System.out.println();
        System.out.println("後序：");
        f_post(root2);
        System.out.println();
        System.out.println("層次遍歷：");
        f_ceng(root2);
        System.out.println();
    }
    //根據先序和中序確定唯一的二叉樹
    public static Tree f_pre_in(int pre[],int in[]){
        if(pre.length==0 || in.length==0){
            return null;
        }
        int pos=-1;
        for(int i=0;i<in.length;i++){
            if(pre[0]==in[i]){
                pos=i;
                break;
            }
        }
        if(pos==-1){
            return null;
        }
        Tree root=new Tree(pre[0]);
        int new_pre_zuo[]=new int[pos];
        for(int i=1;i<=pos;i++){
            new_pre_zuo[i-1]=pre[i];
        }
        int new_in_zuo[]=new int[pos];
        for(int i=0;i<pos;i++){
            new_in_zuo[i]=in[i];
        }
        int new_pre_you[]=new int[in.length-1-pos];
        for(int i=pos+1;i<in.length;i++){
            new_pre_you[i-pos-1]=pre[i];
        }
        int new_in_you[]=new int[in.length-1-pos];
        for(int i=pos+1;i<=in.length-1;i++){
            new_in_you[i-pos-1]=in[i];
        }
        root.left=f_pre_in(new_pre_zuo,new_in_zuo);
        root.right=f_pre_in(new_pre_you,new_in_you);
        return root;
    }
    //根據中序和後序確定唯一的二叉樹
    public static Tree f_in_post(int in[],int post[]){
        if(in.length==0 || post.length==0)
            return null;
        int pos=-1;
        for(int i=0;i<in.length;i++){
            if(in[i]==post[post.length-1]){
                pos=i;
                break;
            }
        }
        if(pos==-1){
            return null;
        }
        Tree root=new Tree(post[post.length-1]);
        int new_in_zuo[]=new int[pos];
        for(int i=0;i<pos;i++){
            new_in_zuo[i]=in[i];
        }
        int new_post_zuo[]=new int[pos];
        for(int i=0;i<pos;i++){
            new_post_zuo[i]=post[i];
        }
        int new_in_you[]=new int[in.length-1-pos];
        for(int i=pos+1;i<in.length;i++){
            new_in_you[i-pos-1]=in[i];
        }
        int new_post_you[]=new int[in.length-1-pos];
        for(int i=pos;i<in.length-1;i++){
            new_post_you[i-pos]=post[i];
        }
        root.left=f_in_post(new_in_zuo,new_post_zuo);
        root.right=f_in_post(new_in_you,new_post_you);
        return root;
    }
    //先序遍歷
    public static void f_pre(Tree root){
        if(root!=null){
           System.out.print(root.value+" ");
           f_pre(root.left);
           f_pre(root.right);
        }
    }
    //中序遍歷
    public static void f_in(Tree root){
        if(root!=null){
            f_in(root.left);
            System.out.print(root.value+" ");
            f_in(root.right);
        }
    }
    //後序遍歷
    public static void f_post(Tree root){
        if(root!=null){
            f_post(root.left);
            f_post(root.right);
            System.out.print(root.value+" ");
        }
    }
    //層次遍歷
    public static void f_ceng(Tree root){
        if(root!=null){
            Queue<Tree> queue=new LinkedList<Tree>();
            queue.offer(root);
            while(queue.size()>0){
                Tree temp1=queue.poll();
                System.out.print(temp1.value+" ");
                if(temp1.left!=null){
                    queue.offer(temp1.left);
                }
                if(temp1.right!=null){
                    queue.offer(temp1.right);
                }
            }
        }
    }
}
class Tree{
    Tree left;
    Tree right;
    int value;
    Tree(int value){
        this.value=value;
    }
}