2009 求数列的和

#include<iostream>
#include<iomanip>
using namespace std;

int main()
{
	int n,m;
	double sum, value;
	while (cin >> n >> m)
	{
		int a = 1;
		value = n;
		for (sum = n; a < m; ++a)
		{
			value = sqrt(value);
			sum = sum + value;
		}
		cout << setprecision(2) << fixed << sum << endl;
	}
	return 0;
}

注意变量定义和初始化的位置。