fun compute(str1: String, str2: String): Int {
    if(str1.length != str2.length)
        throw IllegalArgumentException("left and right strands must be of equal length.")

    var ret = 0
    for((x, y) in str1.zip(str2)) {
        if(x != y)
            ret++
    }
    return ret
}

fun main(){
    val str1 = "GAGCCTACTAACGGGAT"
    val str2 = "CATCGTAATGACGGCCT"
    val hdist = compute(str1, str2)
    println(str1)
    println(str2)
    println("Hamming distance: $hdist")
 }

class Matrix(private val matrix: List<List<Int>>){

    fun column(c: Int): IntArray {
        val col= IntArray(matrix.size) 
        var cindex = 0
        for (r in matrix){
            col[cindex++] = r[c]
        }
        return col
    }

    fun row(r: Int): IntArray {
        return matrix[r].toIntArray()
    }
}

fun main(){
    val m = listOf(
        listOf(1, 2, 3),
        listOf(9, 8, 7),
        listOf(7, 7, 7)
    )
    val matrix = Matrix(m)
    println("Rows:")
    for (n in m.indices) {
        val row = matrix.row(n)
        println(Arrays.toString(row))
    }
    println("Columns:")
    for (n in m.indices) {
        val col = matrix.column(n)
        println(Arrays.toString(col))
    }
}

fun reverse(str: String): String {
    val ret = StringBuilder()
    for (c in str.indices){
        ret.append(str[str.length - c - 1])
    }
    return ret.toString()
}

fun main(){
    val m = "analisi"
val rev = reverse(m)
    println("$m --> $rev")
}

data class Person(val name: String, val surname: String, val id: String)

fun main() {
    var c: Int? = null
    c!!.toString()
}

class Square() : Polygon {
    override val sides: Int = 4
    override var name: String = "square"
}