UVA_474_Heads / Tails Probability

#include<iostream>    
#include<sstream>    
#include<string>    
#include<vector>    
#include<list>    
#include<set>    
#include<map>    
#include<stack>    
#include<queue>    
#include<algorithm>  
#include<bitset>
#pragma warning(disable:4996)    
using std::cin;
using std::cout;
using std::endl;
using std::stringstream;
using std::string;
using std::vector;
using std::list;
using std::pair;
using std::set;
using std::multiset;
using std::map;
using std::multimap;
using std::stack;
using std::queue;
using std::priority_queue;
using std::bitset;
int main()
{
	//freopen("input.txt", "r", stdin);    
	//freopen("output.txt", "w", stdout);
	vector<pair<double, int>>val_pow(1000001);
	val_pow[1].first = 5.0;
	val_pow[1].second = 1;
	for (int i = 2; i <= 1000000; i++)
	{
		val_pow[i].first = val_pow[i - 1].first / 2;
		val_pow[i].second = val_pow[i - 1].second;
		if (val_pow[i].first < 1)
		{
			val_pow[i].first *= 10.0;
			val_pow[i].second++;
		}
	}
	int power;
	while (cin >> power)
	{
		printf("2^-%d = %.3lfe-%d\n",power,val_pow[power].first,val_pow[power].second);
	}
	return 0;
}