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  1. Practice
  2. Functional Programming
  3. Recursion
  4. Pascal's Triangle
  5. Discussions

Pascal's Triangle

  • ankitvij23 + 2 comments

    Easiest SCALA code

    def main(args: Array[String]) {
        val digit = io.Source.stdin.getLines.take(1).map(_.trim.toInt).next()
        def factorial(num: Int) = (1 to num).product
        (0 until digit).foreach(n =>{
            (0 to n).foreach(r => {
                print(factorial(n)/(factorial(r) * factorial(n-r)) + " ")
            })
            println()
        } )
    }
    • MFirat + 0 comments

      thank you!

    • patrick_ce + 1 comment

      I found easier and cleaner solution. Probably also faster thanks to my "if".

      def main(args: Array[String]) {
 val N = scala.io.StdIn.readInt()
 def factorial(num: Int) = (1 to num).product
 for (n <- 0 to N-1) {
  for (r <- 0 to N) {
   if (r <= n) {
    val x = factorial(n) / (factorial(r) * factorial(n - r))
    print(s"$x ")
   } 
  }
  print("\n")
 }
}

      However still it is far from being perfect due to repeted computation of fatorials... there must be some way how to reuse computations from previous levels. I will try to find it on another day.

      • patrick_ce + 0 comments

        Recursive way.

        def pascal(col: Int, row: Int) : Int = {
        if (col == 0 || col == row) 1
        else pascal(col - 1, row - 1) + pascal(col, row - 1)
    }

            def main(args: Array[String]) {
        val N = scala.io.StdIn.readInt()

        for (row <- 0 to N - 1) {
            for (col <- 0 to row) {
                print(pascal(col,row) + " ") 
            }
            print("\n")
        }
    }