Calculate the Levenshtein distance between two strings

Levenshtein.scala

package com.senzari

object Levenshtein {
  
  def distance(start: String, target: String): Int = {

    val slen = start.length()
    val tlen = target.length()
    
    def inner(start: String, target: String): Array[Array[Int]] = {
      val slen = start.length()
      val tlen = target.length()
      var matrix = Array.ofDim[Int](slen+1, tlen+1)
      var matrixCost = Array.ofDim[Int](slen, tlen)
      
      for (i <- 0 to slen) matrix(i)(0) = i
      for (j <- 0 to tlen) matrix(0)(j) = j 

      for (i <- 0 until slen ; j <- 0 until tlen) {
        val (s, t) = (start(i), target(j))
        val cost = if (s == t) 0 else 1
        val costs = List(
            matrix(i)(j+1) + 1,
            matrix(i+1)(j) + 1,
            matrix(i)(j) + cost)
        val min = costs.reduceLeft(Math.min)
        matrix(i+1)(j+1) = min;
      }
    return matrix
    }

    return inner(start, target)(slen)(tlen)
  }
}