evang12
Jan '22

I have been trying for a few hours to solve MATNUM12 (not MATSUM!), with several wrong approaches. Now, I am giving up on this problem, and would like a solution to this problem. Does anyone know the solution to this problem?

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    Jan '22

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    Jan '22
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davidfashion
Jan '22

This is not an easy problem!. But you come to realize that this is one giant conditional statement.

There are 9 possible values each of p0, p1, and q. For each combination of p0, p1, and q, identify how n determines if the generated number is divisible by q. For example:

  1. If p0 = 1, p1 = 1, and q = 2, then no matter the size of n, the generated number is not divisible by 2. (The generated numbers are 1, 11, 111, 1111, etc.)
  2. If p0 = 1, p1 = 2, and q = 2, then the generated number is divisible by 2 when n mod 2 is equal to 0. (The generated numbers are 1, 12, 121, 1212, etc.)

I wrote a great deal of code to determine the patterns. The case where q = 7 was particularly difficult.

Then I wrote a test suite that iterated over all values of p0, p1, and q, and values of n in the range appropriate for the problem. This allowed me to validate all possible combinations were correct.