题目1095：2的幂次方
题目描述：
Every positive number can be presented by the exponential form.For example, 137 = 2^7 + 2^3 + 2^0。
Let’s present a^b by the form a(b).Then 137 is presented by 2(7)+2(3)+2(0). Since 7 = 2^2 + 2 + 2^0 and 3 = 2 + 2^0 , 137 is finally presented by 2(2(2)+2 +2(0))+2(2+2(0))+2(0).
Given a positive number n,your task is to present n with the exponential form which only contains the digits 0 and 2.
输入：
For each case, the input file contains a positive integer n (n<=20000).
输出：
For each case, you should output the exponential form of n an a single line.Note that,there should not be any additional white spaces in the line.
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)
来源：
2006年上海交通大学计算机研究生机试真题
code
java实现
import java.util.*;
public class Main {
public static void main(String args[]) {
Scanner cin = new Scanner(System.in);
int a;
while (cin.hasNext()) {
a = cin.nextInt();
StringBuilder buffer = new StringBuilder();
String aString = Integer.toBinaryString(a);
for(int i = 0; i < aString.length(); i++) {
if(aString.charAt(i) == '1') {
int num = aString.length()-i-1;
if(num == 1)
buffer.append("2+");
else
buffer.append("2(" + changeAllNum(num) + ")+");
}
}
String result = buffer.subSequence(0, buffer.length()-1).toString();
System.out.println(result);
}
}
public static String changeAllNum (int i ) {
if(i<=7)
return changeNum(i);
else {
StringBuilder buff = new StringBuilder("2(2+2(0))");
if(i == 9)
buff.append("+2(0)");
if(i>9)
buff.append("+"+changeAllNum(i-8));
return buff.toString();
}
}
public static String changeNum (int i ) {
switch (i){
case 7:return "2(2)+2+2(0)";
case 6:return "2(2)+2";
case 5:return "2(2)+2(0)";
case 4:return "2(2)";
case 3:return "2+2(0)";
case 2:return "2";
case 1:return "";
case 0:return "0";
}
return "";
}
}
/**************************************************************
Problem: 1095
User: langzimaizan
Language: Java
Result: Accepted
Time:80 ms
Memory:15476 kb
****************************************************************/