Brainteasers: Pattern Pairs

By Genevieve Ludinski

Originally published in EUG #56

In part number five of our Brainteasers serial, we present two tests of memory not dissimilar to the popular newspaper Spot the Difference activity. As always, brief instructions are given on screen before each of the puzzles commences and technical information detailing how the program actually works, plus suggested improvements, follow in this text file. The full collection of Brainteasers is also reviewed this issue.


Nine patterns are displayed on the screen and you are given only a few seconds to compare them and identify the odd one out.

A score sheet will be displayed, showing the number of puzzles completed, number correct and the time and average time taken.

How To Play

Each of the patterns on the screen will be identified by a number, and you must key in the appropriate number as your guess.

If you get the answer wrong, you will be told the correct answer to the accompaniment of a rather low pitched little tune. Get it right, however, and you will hear a pleasant little tune.

After each attempt you will be asked if you wish more (Y for Yes) or wish to stop (N for No).

Remember to press RETURN.

Programming Hints

The filled in triangles are drawn by MOVEing to one point, then MOVEing to another point, then drawing a line to a third point using PLOT 85, and this fills in the space between the first point and the line between the second and third points. This is done in the procedure PROC_PATTERN. The pattern is transferred across and down the screen by adding the appropriate XD or YD or both, depending on the position of the screen.

You could put some more triangles into each pattern by increasing the maximum value of L in procedure PROC_PATTERN. You would also have to reDIMension arrays X,Y and C in line 30. Also the maximum value of I should be increased in line 230.


If you enjoyed Odd One Out in this series, then you will find this following puzzle just as interesting.

There are nine patterns displayed on the screen, in a range of colours, and you have to nominate the pair you believe are a match.

How To Play

Identify your pair, note the numbers alongside and key in your answer. You don't have to key in your answer in strict chronological order; just punch in your numbers and wait. Correct responses will be rewarded with a pleasant little high pitched tune, but wrong answers will be faced with a low pitched little durge.

To continue, type Y at the "More?" prompt. On pressing N, a score sheet will be displayed showing your tries, results, time and average time per problem.

Programming Hints

Each of the pattens is slightly different except for the matching pair. This is done by adding a mixture of H1, H2 and H3 to the corners of the triangles in procedure PROC_PATTERN and H1, H2 and H3 will be different for each pattern except the two that are the same.

If you wish to increase the number of patterns which are the same, then a W3 should be assigned. W3 should be a random number between 1 and 9 inclusive and you should check that it is not equal to W1 or W2. Then change W$ and W1$ and assign four more values, say W2$, W3$, W4$ and W5$ with the string of W1, W2 and W3 arranged in all possible different ways.

Then check for PT to be equal to W1, W2 or W3 in line 720 in procedure PROC_PATTERN to see whether the pattern to be drawn is one of the three identical ones.

Change the input lines 440 to 510 to allow a third number to be keyed in and then check for the six possible values W$, W1$ to W5$.