Task: Bulls and cows_Player
C++: #include <iostream>
#include <sstream>
#include <iomanip>
#include <algorithm>
#include <vector>
#include <time.h>


using namespace std;


const unsigned int LEN = 4;


class CowsAndBulls_Player
{
public:
    CowsAndBulls_Player() { fillPool(); }
    void play() { secret = createSecret(); guess(); }

private:
    void guess()
    {
	pair<int, int> res; int cc = 1;
	cout << endl << " SECRET: " << secret << endl << "==============" << endl;
	cout << "+-----------+---------+--------+\n|   GUESS   |  BULLS  |  COWS  |\n+-----------+---------+--------+\n";
	while( true )
	{
	    string gs = gimmeANumber();
	    if( gs.empty() ) { cout << endl << "Something went wrong with the scoring..." << endl << "Cannot find an answer!" << endl; return; }
	    if( scoreIt( gs, res ) ) { cout << endl << "I found the secret number!" << endl << "It is: " << gs << endl; return; }
	    cout << "|    " << gs << "   |  " << setw( 3 ) << res.first << "    |  " << setw( 3 ) << res.second << "   |\n+-----------+---------+--------+\n";
	    clearPool( gs, res );
        }
    }

    void clearPool( string gs, pair<int, int>& r )
    {
	vector<string>::iterator pi = pool.begin();
	while( pi != pool.end() )
	{
	    if( removeIt( gs, ( *pi ), r ) ) pi = pool.erase( pi );
	    else  pi++;
	}
    }

    string gimmeANumber()
    {
	if( pool.empty() ) return "";
	return pool[rand() % pool.size()];
    }

    void fillPool()
    {
	for( int x = 1234; x < 9877; x++ )
	{
	    ostringstream oss; oss << x;
	    if( check( oss.str() ) ) pool.push_back( oss.str() );
	}
    }

    bool check( string s )
    {
	for( string::iterator si = s.begin(); si != s.end(); si++ )
	{
	    if( ( *si ) == '0' ) return false;
	    if( count( s.begin(), s.end(), ( *si ) ) > 1 ) return false;
	}
	return true;
    }

    bool removeIt( string gs, string ts, pair<int, int>& res )
    {
	pair<int, int> tp; getScore( gs, ts, tp );
	return tp != res;
    }

    bool scoreIt( string gs, pair<int, int>& res )
    {
	getScore( gs, secret, res );
	return res.first == LEN;
    }

    void getScore( string gs, string st, pair<int, int>& pr )
    {
	pr.first = pr.second = 0;
	for( unsigned int ui = 0; ui < LEN; ui++ )
	{
	    if( gs[ui] == st[ui] ) pr.first++;
	    else
	    {
		for( unsigned int vi = 0; vi < LEN; vi++ )
		    if( gs[ui] == st[vi] ) pr.second++;
	    }
	}
    }

    string createSecret()
    {
	string n = "123456789", rs = "";
	while( rs.length() < LEN )
	{
	    int r = rand() % n.length();
	    rs += n[r]; n.erase( r, 1 );
	}
	return rs;
    }

    string secret;
    vector<string> pool;
};

int main( int argc, char* argv[] )
{
    srand( static_cast<unsigned int>( time( NULL ) ) ); CowsAndBulls_Player cb;
    cb.play(); cout << endl << endl;
    return system( "pause" );
}


VB: Option Explicit
 
Sub Main_Bulls_And_Cows_Player()
Dim collSoluces As New Collection, Elem As Variant, Soluce As String
Dim strNumber As String, cpt As Byte, p As Byte
Dim i As Byte, Bulls() As Boolean, NbBulls As Byte, Cows As Byte, Poss As Long
Const NUMBER_OF_DIGITS As Byte = 4
        
        strNumber = CreateNb(NUMBER_OF_DIGITS)
        Debug.Print "TOSS : " & StrConv(strNumber, vbUnicode)
        Debug.Print "---------- START ------------"
        Set collSoluces = CollOfPossibleNumbers
        Poss = collSoluces.Count
        For Each Elem In collSoluces
            
            Debug.Print "Attempt : " & StrConv(Elem, vbUnicode)
            NbBulls = 0: Soluce = Elem
            ReDim Bulls(NUMBER_OF_DIGITS - 1)
            For i = 1 To NUMBER_OF_DIGITS
                If IsBull(strNumber, Mid(Elem, i, 1), i) Then
                    Bulls(i - 1) = True: NbBulls = NbBulls + 1
                    RemoveIfNotBull collSoluces, Mid(Elem, i, 1), i
                End If
            Next i
            Cows = 0
            For i = 1 To NUMBER_OF_DIGITS
                If Not Bulls(i - 1) Then
                    If IsCow(collSoluces, strNumber, Mid(Elem, i, 1), p) Then
                        If Not Bulls(p - 1) Then Cows = Cows + 1
                    End If
                End If
            Next i
            Poss = collSoluces.Count
            Debug.Print "Bulls : " & NbBulls & ", Cows : " & Cows
            If Poss = 1 Then Exit For
        Next
                Debug.Print "---------- THE END ------------"
        Debug.Print "TOSS WAS : " & StrConv(strNumber, vbUnicode) & " We found : " & StrConv(Soluce, vbUnicode)
End Sub
 
Function CreateNb(NbDigits As Byte) As String
Dim myColl As New Collection
Dim strTemp As String
Dim bytAlea As Byte
 
    Randomize
    Do
        bytAlea = Int((Rnd * 9) + 1)
        On Error Resume Next
        myColl.Add CStr(bytAlea), CStr(bytAlea)
        If Err <> 0 Then
            On Error GoTo 0
        Else
            strTemp = strTemp & CStr(bytAlea)
        End If
    Loop While Len(strTemp) < NbDigits
    CreateNb = strTemp
End Function
 
Function CollOfPossibleNumbers() As Collection
Dim TempColl As New Collection
Dim x As String
Dim i As Long
Dim Flag As Boolean
Dim b As Byte
 
    For i = 1234 To 9876
        Flag = False
        For b = 1 To 4
            x = CStr(i)
            If Len(Replace(x, Mid(x, b, 1), "")) < 3 Then
                Flag = True: Exit For
            End If
        Next
        If Not Flag Then TempColl.Add x, x
    Next i
    Set CollOfPossibleNumbers = TempColl
End Function
 
Function IsBull(strgNb As String, Digit As String, place As Byte) As Boolean
    IsBull = (Mid(strgNb, place, 1) = Digit)
End Function

Function IsCow(C As Collection, strgNb As String, Digit As String, place As Byte) As Boolean
    If (InStr(strgNb, Digit) > 0) Then
        IsCow = True: place = InStr(strgNb, Digit)
        RemoveIfNotCow C, Digit
    End If
End Function
 
Sub RemoveIfNotBull(C As Collection, Digit As String, place As Byte)
Dim E As Variant
 
    For Each E In C
        If Mid(E, place, 1) <> Digit Then C.Remove E
    Next
End Sub
 
Sub RemoveIfNotCow(C As Collection, Digit As String)
Dim E As Variant
 
    For Each E In C
        If (InStr(E, Digit) = 0) Then C.Remove E
    Next
End Sub