2020.3.18 Luogu1010 幂次方

递归+二进制
注意判断1

代码：

#include <iostream>
#include <cstdio>

using namespace std;

int n;

inline string div(int x)
{
	if (x == 0)
		return "0";
	if (x == 1)
		return "2(0)";
	if (x == 2)
		return "2";
	int p[20], q = x, id = 0;
	while (q != 1)
	{
		p[id++] = q % 2;
		q /= 2;
	}
	p[id++] = 1;
	string ret;
	if (id - 1 == 1)
		ret = "2";
	else
		ret = "2(" + div(id - 1) + ")";
	for (int i = id - 2; i >= 0; --i)
	{
		if (p[i] == 1 && i != 1)
			ret += "+2(" + div(i) + ")";
		if (p[i] == 1 && i == 1)
			ret += "+2";
	}
	return ret; 
}

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