Blue Bridge Cup basic exercises VIP FJ string of questions - JAVA

Problem Description
　　FJ in the sand table to write some string like this:
　　A1 = "A"
　　A2 = "ABA"
　　A3 = "ABACABA"
　　A4 = "ABACABADABACABA"
　　... ...
　　
　　you can find out the rules and write them all columns AN it?
　　
The input format
　　is only a few: N ≤ 26.
　　
Output format
　　requested output a corresponding string of AN, to a newline character. Output must not contain extra space or line feed, carriage return.
　　
Sample input
3

Sample output
ABACABA

PS: seen from the meaning of the questions: A1 = "A"; A2 = A1 + "B" + A1; A3 = A2 + "C" + A2;

! So when n = 1, having the formula: An = An-1 + 'n represented by uppercase alphabetic characters' + An-1;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc=new Scanner(System. in);
		int n=sc. nextInt(); 
		
		FJStr(n);
	}
	
	static void FJStr(int n){	
		//递归出口
		if(n == 1){
			System.out.print("A");
		}
		else{
			//相当于求和  --> An = An-1 + n表示的字母 + An-1
			FJStr(n-1);
			System.out.print((char)(n+64)); //将此时的行数转换为字母字符
			FJStr(n-1);
		}		
	}

}