Project Euler：Problem 16 Power digit sum

2¹⁵ = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26.

What is the sum of the digits of the number 2¹⁰⁰⁰?

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

int main()
{
	string s = "1";
	for (int i = 1; i <= 1000; i++)
	{
		int len = s.length();
		int flag = 0;
		for (int j = len - 1; j >= 0; j--)
		{
			int tp = (s[j] - '0') * 2 + flag;
			flag = tp / 10;
			s[j] = tp % 10 + '0';
		}
		if (flag != 0)
		{
			s = "1" + s;
		}
		
	}
	int len = s.length();
	int res = 0;
	for (int i = 0; i < len; i++)
	{
		res += s[i] - '0';
	}
	cout << res << endl;
	system("pause");
	return 0;
}

Project Euler：Problem 16 Power digit sum

原文：http://blog.csdn.net/youb11/article/details/46285251