PTA 重建二叉树 java

题目链接：​​https://pintia.cn/problem-sets/1120858298571182080/problems/1120858729171013632​​

package pat树;
//ac
import java.util.Scanner;

  public class Main87重建二叉树 {
      static String a;
      static String b;
      static node root;
      static int n;
      public static node build(int pl,int pr,int il,int ir) {
        if(il>ir)return null;
        node jiedian=new node();
        char v=a.charAt(pl);
        jiedian.v=v;
        int i;
        for(i=0;i<=n;i++)if(b.charAt(i)==v)break;
        int num=i-il;
        jiedian.le=build(pl+1,pl+num,il,i-1);
        jiedian.ri=build(pl+num+1,pr,i+1,ir);
        return jiedian;
      }
      public static void print(node root) {
        if(root!=null) {
          print(root.le);
          print(root.ri);
          System.out.print(root.v);
        }
      }
    public static void main(String[] args) {
      Scanner in=new Scanner(System.in);
      while(in.hasNext()) {
        a=in.next();
        if(a.equals("EOF"))break;
        b=in.next();
        n=a.length()-1;
        root=build(0,n,0,n);
        print(root);
        System.out.println();
      }

    }

  }
  class node{
    char v;
    node le;
    node ri;
  }