19-算法训练 2的次幂表示

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner cin = new Scanner(System.in);
		StringBuilder ans = new StringBuilder();
		long n = cin.nextLong();
		
		ans = toTwo(n);
		
//		ans.append("a");
//		System.out.println("a".equals(ans.ch)));
		
		System.out.println(ans);
	}
	public static StringBuilder toTwo(long n) {
		StringBuilder ans = new StringBuilder();
		StringBuilder two = new StringBuilder();
		while(n != 0) {
			if(n % 2 == 0) {
				two.append("0");
			}
			else {
				two.append("1");
			}
			n /= 2;
		}
//		System.out.println(two);
//		System.out.println(two.charAt(0));
		int len = two.length();
		int flag = 0;
		for(int i = len - 1; i >= 0; i--) {
			if(two.charAt(i) == ‘1‘) { //注意StringBuilder.charat()返回的是char
				if(flag == 1) {
					ans.append("+");
				}
				else {
					flag = 1;
				}
				if(i == 0) {
					ans.append("2(0)");
				}
				else if(i == 1) {
					ans.append("2");
				}
				else if(i == 2) {
					ans.append("2(2)");
				}
				else {
					ans.append("2(" + toTwo(i) + ")");
				}
			}
		}
		return ans;
	}
}
//137
//2(2(2)+2+2(0))+2(2+2(0))+2(0)
//样例输入
//1315
//样例输出
//2(2(2+2(0))+2)+2(2(2+2(0)))+2(2(2)+2(0))+2+2(0)