USACO 1.2-Palindromic Squares

/*
ID: m1590291
PROG: palsquare
LANG: C++
*/
#include <fstream>
#include <string>
using namespace std;

char NUMBER[20] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
                   'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J'};

string convert(int, int);
bool is_plalindrome(string);

int main()
{
    ifstream fin("palsquare.in.txt");
    ofstream fout("palsquare.out.txt");

    int b;
    fin >> b;

    string num, square;
    for (int i = 1; i <= 300; ++i) {
        num = convert(i, b);
        square = convert(i*i, b);
        if (is_plalindrome(square))
            fout << num << " " << square << "
";
    }

    return 0;
}

string convert(int n, int b)
{
    string number;
    while (n) {
        number.insert(number.begin(), NUMBER[n%b]);
        n /= b;
    }
    return number;
}

bool is_plalindrome(string s)
{

    for (string::iterator back = s.begin(), forward = s.end()-1;
         back < forward; ++back, --forward) {
        if (*back != *forward)
            return false;
    }
    return true;
}