http://community.topcoder.com/stat?c=problem_statement&pm=12169

PlatypusDuckAndBeaver.cpp

#include <iostream>

using namespace std;

struct Animal
{
    int feet;
    int bill;
    int tail;
};

Animal duck     = { 2, 1, 0 };
Animal beaver   = { 4, 0, 1 };
Animal platypus = { 4, 1, 1 };

int minimumAnimals( int webbedFeet, int duckBills, int beaverTails )
{
    int i, j, k;
    
    for( i=0; i<=1000; i++ ) // duck
    {
        for( j=0; j<=1000; j++ ) // beaver
        {
            for( k=0; k<=1000; k++ ) // platypus
            {
                if( duck.feet*i + beaver.feet*j + platypus.feet*k == webbedFeet &&
                    duck.bill*i + beaver.bill*j + platypus.bill*k == duckBills &&
                    duck.tail*i + beaver.tail*j + platypus.tail*k == beaverTails )
                {
                    goto found;
                }
            }
        }
    }
    
found:
    
    return i+j+k;
}

int main()
{
    cout << minimumAnimals( 10, 2, 2 ) << endl;
    cout << minimumAnimals( 1000, 200, 200 ) << endl;
}