import scala.collection.mutable.ListBuffer
object error {
  var error: Boolean = false
}

object Main {
  def main(args: Array[String]) {
    val main: Main = new Main()
    println("Enter your values, line by line, in the form X X X X X X X X X below.")
    var multiArray = Array.ofDim[Int](9, 9)
    multiArray = main.getInput
    main.duplicateLine(multiArray)
    main.duplicateColumn(multiArray)
    for (i <- 0.until(3); j <- 0.until(3)) {
      main.threeByThree(multiArray, i, j)
    }
    if (error.error == false) {
      println("This is a valid sudoku input!")
    }
  }
}

class Main {

  def getInput = {
    val array: Array[Int] = Array.ofDim(9)
    val multiArray: Array[Array[Int]] = Array.ofDim[Int](9, 9)
    var s: String = null
    for (i <- 0.until(9)) {
      s = scala.io.StdIn.readLine()
      println(s + "      <-- row entered, continue below:")
      var k: Int = 0
      for (j <- 0.until(9)) {
        multiArray(i)(j) = s.charAt(k).asDigit
        k = k + 2
      }
    }
    println("\n")
    multiArray.foreach(row => println(row.mkString(" ")))
  multiArray
  }

  def duplicateLine(array: Array[Array[Int]]): Unit = {
    for (i <- 0.until(9)) {
      var duplicate = new ListBuffer[Integer]

      for (j <- 0.until(9)) {
        val valueToCheck: Int = array(i)(j)
        if ((duplicate.contains(valueToCheck))) {
          error.error = true
          println("Rule violated in row " + (i + 1))
        }
        else {
          duplicate += (valueToCheck)
        }
      }
    }
  }

  def duplicateColumn(array: Array[Array[Int]]): Unit = {
    for (j <- 0.until(9)) {
      var duplicatec = new ListBuffer[Integer]
      for (i <- 0.until(9)) {
        val valueToCheck: Int = array(i)(j)
        if (duplicatec.contains(valueToCheck)) {
          error.error = true
          println("Rule violated in column " + (j + 1))
        }
        else {
          duplicatec += (valueToCheck)
        }
      }
    }
  }

  def threeByThree(array: Array[Array[Int]], row: Int, col: Int): Unit = {
    var duplicatet = new ListBuffer[Integer]
    for (i <- 0.until(3); j <- 0.until(3)) {
      val valueToCheck: Int = array(i + (row * 3))(j + (col * 3))
      if (duplicatet.contains(valueToCheck)) {
        error.error = true
        row match {
          case 0 =>
            if (col == 0) {
              println("Rule violated in 3x3 grid upper left")
            } else if (col == 1) {
              println("Rule violated in 3x3 grid upper middle")
            } else {
              println("Rule violated in 3x3 grid upper right")
            }
          case 1 =>
            if (col == 0) {
              println("Rule violated in 3x3 grid middle left")
            } else if (col == 1) {
              println("Rule violated in 3x3 grid middle")
            } else {
              println("Rule violated in 3x3 grid middle right")
            }
          case 2 =>
            if (col == 0) {
              println("Rule violated in 3x3 grid bottom left")
            } else if (col == 1) {
              println("Rule violated in 3x3 grid bottom middle")
            } else {
              println("Rule violated in 3x3 grid bottom right")
            }
        }
      }
      else {
        duplicatet += (valueToCheck)
      }
    }
  }
}
by

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Read input from STDIN in Scala

OneCompiler's Scala online editor supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample Scala program which takes name as input and prints hello message with your name.

object Hello {
	def main(args: Array[String]): Unit = {
	  val name = scala.io.StdIn.readLine()        // Read input from STDIN
    println("Hello " + name ) 
	}
}

About Scala

Scala is both object-oriented and functional programming language by Martin Odersky in the year 2003.

Syntax help

Variables

Variable is a name given to the storage area in order to identify them in our programs.

var or val Variable-name [: Data-Type] = [Initial Value];

Loops and conditional statements

1. If family:

If, If-else, Nested-Ifs are used when you want to perform a certain set of operations based on conditional expressions.

If

if(conditional-expression){    
//code    
}

If-else

if(conditional-expression) {  
//code if condition is true  
} else {  
//code if condition is false  
}

Nested-If-else

if(condition-expression1) {  
//code if above condition is true  
} else if (condition-expression2) {  
//code if above condition is true  
}  
else if(condition-expression3) {  
//code if above condition is true  
}  
...  
else {  
//code if all the above conditions are false  
}

2. For:

For loop is used to iterate a set of statements based on a criteria.

for(index <- range){  
  // code  
}

3. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while(condition) {  
 // code 
}

4. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {
  // code 
} while (condition)

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity.

def functionname(parameters : parameters-type) : returntype = {   //code
}

Note:

You can either use = or not in the function definition. If = is not present, function will not return any value.