Project Euler Problem 99 Largest exponential

Largest exponential

Problem 99

Comparing two numbers written in index form like 2¹¹ and 3⁷ is not difficult, as any calculator would confirm that 2¹¹ = 2048 < 3⁷ = 2187.

However, confirming that 632382⁵¹⁸⁰⁶¹ > 519432⁵²⁵⁸⁰⁶ would be much more difficult, as both numbers contain over three million digits.

Using base_exp.txt (right click and 'Save Link/Target As...'), a 22K text file containing one thousand lines with a base/exponent pair on each line, determine which line number has the greatest numerical value.

NOTE: The first two lines in the file represent the numbers in the example given above.

C++:

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

using namespace std;

int main()
{
    long b, e, max, temp;
    int ans=0, no=0;
    string filename;

    cin >> filename;
    ifstream inf(filename, ios::in);

    char c;
    while(inf >> b >> c >> e) {
        no++;
        temp = (long) (e * log(b));
        if(temp > max) {
            max = temp;
            ans = no;
        }
    }

    cout << ans << endl;

    inf.close();

    return 0;
}