countChange

package recfun

object Main {
  def main(args: Array[String]) {
    println("Pascal's Triangle")
    for (row <- 0 to 10) {
      for (col <- 0 to row)
        print(pascal(col, row) + " ")
      println()
    }
  }

  /**
   * Exercise 1
   */
  def pascal(c: Int, r: Int): Int =
    if (c == 0 || c == r) 1 else (pascal(c - 1, r - 1) + pascal(c, r - 1))

  /**
   * Exercise 2
   */
  def balance(chars: List[Char]): Boolean = {
    require(!chars.isEmpty)

    def countParentheses(chars: List[Char], acc: Int): Int = {
      if (acc < 0) -1
      else if (chars.isEmpty) acc
      else countParentheses(chars.tail, acc + typeChar(chars.head))
    }

    def typeChar(char: Char): Int = {
      if (char == '\u0028') 1
      else if (char == '\u0029') -1
      else 0
    }

    (countParentheses(chars, 0) >= 0)
  }

  /**
   * Exercise 3
   */

  def countChange(money: Int, coins: List[Int]): Int = {
    if (money < 0) 0
    else if (money == 0) 1
    else if (coins.isEmpty) 0
    else (countChange(money - coins.head, coins) + countChange(money, coins.tail))
  }
}