算法训练 2的次幂表示

Problem:

Hint: 

1. 看这题目肯定是要使用递归的
2. 先将该数转化为二进制的字符串
3. 然后遍历该字符串,计算其二进制中字符为'1'的位数,如果该位数是2或者是0直接拼接上2(0)或者2(2)
4. 如果该位数是1那么就拼接上2就行
5. 如果不是0,1,2那么就digui递归该位数然后再拼接

AcCode:

import java.util.Scanner;

public class Main{
	public static String getStr(int num) {
		boolean isFirst = true;
		StringBuffer buffer = new StringBuffer("");
		String binStr = Integer.toBinaryString(num);
		for (int i = 0; i < binStr.length(); i++) {
			if(binStr.charAt(i)=='1') {
				if(isFirst) {
					buffer.append("2(");
					isFirst = false;
				}else {
					buffer.append("+2(");
				}
				int ws = binStr.length()-1-i;//2进制进位
				if(ws==0 || ws==2) {
					buffer.append(ws);
				}else if(ws==1){
					buffer.deleteCharAt(buffer.length()-1);
					continue;
				}else {
					buffer.append(getStr(ws));
				}
				buffer.append(")");
			}
		}
		return buffer.toString();
	}
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int num = in.nextInt();
		System.out.println(getStr(num));
	}
}