Micro­power

For convenience in programming and display, the numbers 1 to 19 are represented by the letters A to S. At the start of the search, and when a solution has been found, the program pauses to allow the position to be noted down. Any key depression will cause the search to be resumed. The program terminates when there are no further possible arrangements.

The first solution will be found in just over four minutes, and the second in another two and a half minutes (at 4 Mhz). Further solutions will require considerably more patience, but those interested enough may wish to run the program exhaustively in order to uncover all the possible arrangements and discover if there exists more than one unique solution.

PROGRAM LISTING