洛谷P1010 [NOIP1998 普及组] 幂次方进阶解法

#include<iostream>
#include<string>
#include<cmath>

using namespace std;
int n;

string trans(int n)
{
	string s;
	int m = n;
	for (; m != 0;)
	{
		int i;
		for (i = 0; pow(2, i) <= m; i++) {}
		if (1 == i)
			s += "+2(0)";
		else if (2 == i)
			s += "+2";
		else
			s += "+2(" + trans(i - 1) + ")";
		m -= pow(2, i - 1);
	}
	return s.substr(1);
}

int main()
{
	cin >> n;
	cout << trans(n);
	return 0;
}