I have the task to create a password validation that has to consider some things. The only problem I have is that one of the criteria of the password validation is that the password must not contain any sequences, e.g. (12345), (abcdef), (asdfghjk). I have already searched a lot and do not know how to implement this. Can anyone help.

CodePudding user response：

Since you didn't give much detail into what code you already have and what you're stuck on about the logic, here's a very generalized description of a strategy you could use to do this:

1. Create a List<Iterable<Char>> that contains all the possible strings of characters that could be considered a range. For example:

    val charRuns = listOf(
        '0'..'9',
        'a'..'z',
        'A'..'Z',
        "qwertyuiop".asIterable(),
        //...
    )

2. Iterate these runs to fill a MutableMap<Char, MutableSet<Char>>, where the keys are any of the characters from the runs, and the values are sets of all the chars that if they appear next in a string should be considered a consecutive sequence.

3. Iterate the potential password String, using the map to check the subsequent Char of each Char to see if it should be considered part of a sequence. Use a counter variable to count the current size of sequence found so far, and reset it whenever a non-sequence is found. If it ever rises above your threshold for allowable sequence size, reject the password immediately.

CodePudding user response：

This is how I implemented it. I also check that there is no sequence in backwards, for example (4321, dcba).

private fun noSequenzes(password: String) : Boolean {
    val charRuns = listOf(
        '0'..'9',
        'a'..'z',
        'A'..'Z',
        "qwertzuiop".asIterable(),
        "asdfghjklöä".asIterable(),
        "yxcvbnm".asIterable()
    )
    var map = emptyMap<Char, MutableSet<Char?>>()
    charRuns.forEach { run ->
        run.forEach { char ->
            val charsToAdd = mutableSetOf(run.elementAtOrNull(run.indexOf(char)   1))
            if (run is CharRange) {
                charsToAdd.add(run.elementAtOrNull(run.indexOf(char) - 1))
            }
            if (map.contains(char)) {
                map.get(char)!!.addAll(charsToAdd)
            }
            else {
                map = map.plus(Pair(char, charsToAdd))
            }
        }
    }
    var sequenceCounter = 1
    var recentChar: Char? = null
    password.toCharArray().forEach { c ->
        recentChar?.let { rc ->
            val isSequence = map.any { me -> me.key == rc && me.value.contains(c) }
            if (isSequence) {
                sequenceCounter = sequenceCounter   1
            }
            else {
                sequenceCounter = 1
            }
            if (sequenceCounter >= 3) {
                return false
            }
        }
        recentChar = c
    }
    return true
}