Butler’s Apps

Application Development for iPhone, iPad, and iPod touch

Killer Aid Help

The Killer Aid App is divided into four regions, as illustrated in the following diagram (Note this shows the display for an iPhone. The iPad version is similar, except the results appear in the detailed area on the right hand side of the screen).

The following sections describe each of these regions in turn.


The header region gives the title of the screen and also provides the Support option button. Pressing this button gives the following menu:

  • Help - this content
  • Solving Strategies - tips on how to solve Killer Sudoku puzzles
  • Bibliography - references to Killer Sudoku puzzle sources
  • Rate App - brings up the App Store review page
  • Suggest New Feature - email any suggestions
  • Report Bug - email details of any bugs


The input region shows the settings for the current cage cell size and sum.

Filter settings are also highlighted by their on/off status as well as background colour (see table below).

 Filter  State  Colour
 All  Off  White
 Exclude  On  Red
 Include AND  On  Green
 Include OR Set 1  On  Red
 Include OR Set 2  On  Orange
 Include OR Set 3  On  Yellow
 Include OR Set 4  On  Blue
 Include OR Set 5  On  Violet
 Include OR Set 6  On  Green


Provides a list of all combinations that add up to the displayed sum. Note that the list excludes combinations that have been removed by the filter settings. Manually deleted combinations are shown with a double line though them. The results header includes an indication of whether or not duplicates are allowed.


The tools region provides three tools to assist solving Killer Sudoku puzzles, namely:


The Edit tool is used to determine all possible combinations of cell values that can add up to the cage's sum. It provides a picker control to enable easy entry of the Sum and the number of cage Cells. On touching the "Done" button the Edit tool is dismissed revealing the Results with any duplicate values highlighted in Red. However if the "Cancel" button is touched the Edit tool is dismissed leaving the Sum, Cells and Results values unchanged.

Normally each result is shown without duplicates. However if the "Duplicates" switch is turned on then duplicates are allowed for each result.


The Filter tool helps to reduce the possible combinations of each cage. It subdivides into three filters, namely:

  • Exclude
  • Include AND
  • Include OR


The Exclude filter is used when it is known that a cage cannot contain certain cell values (e.g. the cage is in a row, column, or block that already contains those numbers).


When a cage is know to include specific cell values, then the "Include AND" filter can be used. This reduces the number of combinations down to those that include these values.

The "Include OR" filter is used when there is a choice between sets of different cell values. For example if a cage is known to contain either a (3,5), (3,9) or (5,9) then the Include OR filter will show only results that include one or more of these sets. The Include OR filter works slightly differently from the previous filters in that each press of the "OR" button selects a different coloured set (indicated by its background colour). There are six colours in all (red, orange, yellow, blue, violet and green) making it possible to OR up to 6 sets of cell values. Refer to the Solving Strategies for examples of using this filter.

It is possible to combine all the above filters to maximise the reduction in possible combinations for a cage.

The "C" button (Clear) clears all filter settings for the currently displayed filter, whereas the "CA" button (Clear All) clears all three-filter type settings.

On the iPad version, the filtered results can be seen immediately, without the need to press the "Done" button, since the results are always visible. In this case the "Done" button is simply used to dismiss the filter tool and confirm these results. However on the iPhone the "Done" button must be touched to dismiss the filter tool before the results are visible. In both versions the "Cancel" button will dismiss the filter tool and return the results to their values before the latest filter was applied.

Results values can be deleted by touching the relevant entry in the results table. Touching again will remove this filter.

Lastly the current active filter list is displayed below the filter buttons. This list can be scrolled horizontally when it exceeds the display width.


A Calculate tool is provided to simplify use of some of the Killer Sudoku solving strategies. The Calculator has been optimised for solving Killer Sudoku puzzles. In particular it has the following features:

  • A dedicated 45 button - this is a frequently entered value
  • A "+" and "-" and bracket buttons - useful for "innie" and "outie" calculations
  • A "x" button - useful when considering multiple rows, columns or blocks (i.e. N x 45)
  • A list of the currently entered keystrokes - can be scrolled horizontally to view strings that exceed the display width

On start up the calculate tool shows the current sum. After a calculation is performed, touching the "Done" button will transfer the calculated sum to the Sum field, providing it is within the legal range. Note that the Cell field will be adjusted, if required, to bring the sum into a legal range. Alternatively, touching the "Cancel" button will result in leaving the Cell/Sum combination unchanged. In both cases the Calculate tool will be dismissed.

Because the results are always visible on the iPad version, the Cell/Sum fields will be updated after pressing the "=" key and the results updated accordingly. The "Done" button works in the same manner as for the iPhone version, but the "Cancel" button returns the Cell/Sum to their previous values.



© Butler's Apps 2017