bool division_bad_parity_hack( const method &m, const change &c,
size_t div_start, size_t cur_div_len )
{
// It should be possible to do this easily without calculating rows.
row r( c.bells() );
vector< row > rows( 1, r );
rows.reserve( cur_div_len );
for ( int i = div_start; i < m.length(); ++i )
{
r *= m[i];
rows.push_back( r );
}
rows.push_back( r * c );
assert( rows.size() == cur_div_len );
size_t even[2] = { 0u, 0u }, odd[2] = { 0u, 0u };
for ( unsigned int i = 0; i < rows.size(); ++i )
{
if ( rows[i].sign() == +1 )
++even[i%2];
else
++odd[i%2];
}
if ( even[0] != odd[0] || even[1] != odd[1] )
return true; // Bad
return false; // OK
}
bool is_too_many_places( const method &m, const change &c, size_t max,
size_t stopoff )
{
for ( int i=0; i<c.bells(); ++i )
if ( c.findplace(i) )
{
size_t count(2u);
for ( ; count <= size_t(m.length())+1; ++count ) {
size_t o = m.length() - count + 1;
if ( o == stopoff || !m[o].findplace(i) )
break;
}
if ( count > max )
return true;
}
return false;
}
bool is_division_false( const method &m, const change &c,
size_t div_start, size_t cur_div_len )
{
size_t const len = m.length();
if ( len - div_start < 3 || len - div_start == cur_div_len-1 )
return false;
row r( c.bells() );
vector< row > rows( 1, r );
rows.reserve( cur_div_len );
for ( int i = div_start; i < len; ++i )
{
r *= m[i];
rows.push_back( r );
}
if ( find( rows.begin(), rows.end(), r * c ) != rows.end() )
return true;
return false;
}