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Kotlin for java refugees

Day 2

Challenge

We need to confirm that passwords meet the corporate policy.

1-3 a: abcde
1-3 b: cdefg
2-9 c: ccccccccc

Each line contains the password policy and the password.

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Our task is to check that the password :

  • is valid
  • conforms to the given policy

The policies are different in the first and the second parts of the challenge.

Part 1

The password policy indicates the lowest and highest number of times a given letter must appear for the password to be valid.
img.png
For example, 1-3 a means that the password must contain a at least once and at most 3 times.

1-3 a: abcde is valid : contains 1 `a` within the limits of the 3 occurences.
1-3 b: cdefg is invalid : no `b` within the limits.
2-9 c: ccccccccc is valid : contains 9 `c` within the limits of the 9 occurences.

Part 2

In the second part, the policy describes two positions in the password :

  • where 1 means the first character
  • 2 means the second character, and so on…
  • indexing starts at 1, not 0

Exactly one of these positions must contain the given letter. Other occurrences of the letter are irrelevant.

Given the same example list from above:

1-3 a: abcde is valid: position 1 contains a and position 3 does not.
1-3 b: cdefg is invalid: neither position 1 nor position 3 contains b.
2-9 c: ccccccccc is invalid: both positions 2 and position 9 contain c.

Exercise

  • How would you solve it ? - 10’
    • In group, write down the pseudo algorithm (in comments for example)
  • Collective debriefing - 10`
    • Let’s agree on how to implement it
    • What do we need to write it in Kotlin ?
  • Step by step + koans - 20’
  • Let’s implement the solution - 20’
  • Collective debriefing - 10’
    • What can be improved ?
  • Go back to the Step by step page on step 4 - 10’
    • Let’s refactor / improve our code
  • Debriefing - 5’
    • What do you think about Kotlin after those 2 days ?

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