Blue Bridge cup of java training algorithm represents the power of two

Training algorithm represents the power of two

Resource constraints

Time limit: 1.0s Memory Limit: 512.0MB

Problem Description

Any positive integer may be represented in binary, for example: 137 is represented as 10001001 binary.
　　This represents a binary power of 2, written in the form and, so that the top surface of the high-power, gives the following expression: 137 = 2 ^{7 + 2} 3 + 2 ^ 0
　　Now agreed with powers of brackets He indicates that a ^ b is expressed as a (b)
　　In this case, 137 may be expressed as: 2 (7) + 2 (3) + 2 (0)
　　further: 7 = 2 ^{2 + 2 + 2} 0 (2 ^ 1 with 2 represents a)
　　3 + 2 ^ 2 = 0
　　so finally 137 can be expressed as: 2 (2 (2) + 2 + 2 (0)) 2 + (2 + 2 (0)) 2 + (0)
　　Another example: 1315 2 = ^{10 + 2} 8 + 2 + 2 + 1 ^ 5
　　it can be expressed as the final 1315:
　　2 (2 (2 + 2 (0)) + 2) + 2 (2 (2 + 2 (0))) + 2 (2 (2) + 2 (0)) + 2 + 2 (0)

Input Format

Positive integer (1 <= n <= 20000)

Output Format

In line with the agreed n represents 0,2 (no spaces in the representation)

import java.util.Scanner;


public class Main {
    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);
        int n=in.nextInt();

        System.out.println( toResult(n));


    }
    //转换为2进制
    public static String toBin(int n){
        return Integer.toBinaryString(n);
    }
    //第一步
    public static String toResult(int n){
        StringBuilder sb=new StringBuilder();
        String str=toBin(n);
        int len=str.length()-1;
        for (char c:str.toCharArray()) {
            if(c=='1'){
                if(len==2)
                    sb.append("2("+len+")");
                else if(len==1)
                    sb.append("2");
                else
                    //递归输出
                    sb.append("2("+toResult(len)+")");
                if(len!=0)
                    sb.append("+");
            }
            len--;
        }
        if(sb.toString().equals("")||sb.equals(null))
            return "0";
        if(sb.charAt(sb.length()-1)=='+')
            sb.deleteCharAt(sb.length()-1);
        return sb.toString();
    }
}