Question

我编写了以下代码来打印Fibonacci序列中的前10个数字。我期待输出0,1,1,2,3,5,8,13,21,34。相反，我得到0,1,2,3,5,8,13,21,34,55。这是代码 -

var a = 0
var b = 0
var i = 0

while(i < 10) {
  val c = a +b
 a = b
 b = c
 i = i + 1
 if (a < 1) a = 1

println(b)
 }

Answer 1

这应该有效：

var a = 0 
var b = 1 
var i = 0 

while(i < 10) {
  println(a)
  val c = a + b 
  a = b 
  b = c 
  i = i + 1 
}

但这不起作用，所以不是真正的scala

Answer 2

这是一个递归解决方案，展示了一些基本的Scala功能：

// Function definitions can have types with default values
def fib(a: Int = 0, b: Int = 1, count: Int = 2): List[Int] = {

  // Calculate the next value
  // In functional programming we prefer immutability so always try to use val instead of var
  val c = a + b

  // Stopping criteria, send back a list containing the latest value
  if (count >= 10) {
    List(c)
  }

  // If this is the first iteration create the first few fibonacci numbers, and make a recursive call
  // Adding one list to another is done using the ++ function
  else if (a == 0 && b == 1) {
    List(a, b, c) ++ fib(b, c, count + 1)
  }

  // If this wasn't the first iteration, just add the latest element and make the recursive call
  else {
    c +: fib(b, c, count + 1)
  }
}

// Since we gave default values the function parameters, you don't need to pass any when you call the function here
println(fib())

无法从Scala代码获取正确的Fibonacci序列

2 个答案: