Re: any suggestion to improve the following code?

#include <iostream>
#include <fstream>
#include <algorithm>

using namespace std;

#include <ext/hash_map>
using namespace __gnu_cxx;

#include <boost/filesystem/convenience.hpp>

hash_map<unsigned int, unsigned int, hash<unsigned int> > steps;

// Computes number of steps for number n according
// to Collatz Conjecture (3n+1 problem)
// http://en.wikipedia.org/wiki/Collatz_conjecture
//
// To speed things up, results are book kept, saved/restored
// when program starts/finishes.
//
// In the recursively computing function, the steps to finish a
// a number is always memorized and retrieved on demand.
unsigned int compute_steps(int n){
    // shortcut to retrieve memorized steps[n]
    if(steps[n])
        return steps[n];
    if(n == 1) return 1;
    if(n%2)
        n = 3*n+1;
    else
        n = n/2;
    cout << ' ' << n;
    // shortcut to memorize steps[n]
    steps[n] = compute_steps(n);
    return steps[n] + 1;
}

int main(){
    boost::filesystem::path file("record_h.txt");

    unsigned int two[2];
    if(exists(file)){
        ifstream inf("record_h.txt", ios::binary);
        while(inf.read((char *)two, 2*sizeof(unsigned int)))
            steps[two[0]] = two[1];
        inf.close();

    }