check bottom - left cell
if ( ( elex < m - 1 ) and ( eley > 0 ) and ( rect [ elex + 1 ] [ eley - 1 ] == 0 ) ) : NEW_LINE INDENT rect [ elex + 1 ] [ eley - 1 ] = 1 NEW_LINE v = [ elex + 1 , eley - 1 ] NEW_LINE qu . put ( v ) NEW_LINE DEDENT