Blackone

// 3nplus1problem.cpp
// Author: Jose E Cartagena Alicea
// Date: April 22, 2009

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



// Prototypes
void readFile(int &n1, int &n2, ifstream &inFile);
void writeFile(int n1, int n2, int max, ofstream & outFile);
int checkIterations(int n1, int n2);
int iterations(int value);

int main()
{
    ifstream inFile;
    ofstream outFile;
    int n1, n2;

    try
    {
    inFile.open("input.in");
    outFile.open("output.out");
    }
    catch(...)
    {
        cout << "Files can not be opened\n";
        cin.ignore();
        return 1;
    }

    readFile(n1, n2, inFile);
    while(!inFile.eof())
    {
        int max = checkIterations(n1, n2);
        writeFile(n1, n2, max, outFile);
        readFile(n1, n2, inFile);
    }

    cout << "Finishing the problem\n";
    cin.ignore();
    inFile.close();
    outFile.close();
    return 0;
}

// This function is to read the data from the file called input.in
void readFile(int &n1, int &n2, ifstream &inFile)
{
    try
    {
        inFile >> n1 >> n2;
    }
    catch(...)
    {
        cout << "The expression was in an incorrect format\n";
    }
}

// This function is to write the results into the file output.out
void writeFile(int n1, int n2, int max, ofstream &outFile)
{
    outFile << n1 << " " << n2 << " " << max << endl;
}

// This function call the function iterations to check the iterations of
// each number then compare them to return the greater value
int checkIterations(int n1, int n2)
{
    int max = 1;
    for(int i = n1; i <= n2; i++)
    {
        int temp = iterations(i);
        if(temp > max)
            max = temp;
    }
    return max;

}

// This module checks the iterations of the value sended to it
int iterations(int value)
{
    int count = 1;
    while(value != 1)
    {
        if(value % 2 == 0)
            value = value / 2;
        else
            value = value * 3 + 1;

        count ++;
    }
    return count;
}