斯卡拉：使用遞歸的利率計算器

Question

我試圖在這個利率計算器上使用遞歸。現在它會打印費率和每月付款等事情，但我希望它能夠打印每個月的付款金額和其他所有內容（而不僅僅是總額），直到用戶不必支付更多費用爲止。有沒有辦法做到這一點使用遞歸？

import io.StdIn._ 

println("Enter the house loan ammount: ") 
val loan = readInt() 

println("Enter the number of years you want to take to pay off the loan: ") 
val years = readInt() 

println("Enter the annual interest rate") 
val interestRate = readInt() 

val monthlyPayment = (loan*(interestRate/12))/(1- 
(1+interestRate/12)^years*12) 

val totalPayment = monthlyPayment*years*12 

def monthlyPayment2(monthlyPayment:Int):Unit = { 
if (monthlyPayment>0){ 
    println(monthlyPayment) 
monthlyPayment2((loan*(interestRate/12))/(1-(1+interestRate/12)^years*12)) 
} 
} 
println ("The monthly payment is:"+monthlyPayment) 
println("The total payment is:" + totalPayment) 

Answer 1

月付是一樣的每月（除，也許是最後一個），所以，如果你知道的金額，這是很簡單的：

@tailrec 
final def printMonthly(
    principal: Double, 
    amount: Double, 
    month: Int = 1 
): Unit = { 
    val paid = amount*(month-1) 
    val left = principal - paid 
    if(left <= amount) { 
    println(s"$month: Payment: $left, Total: $principal, Remaining: 0") 
    } else { 
    println(
    s"$month: Payment: $amount, Total: ${paid + amount}, Remaining: ${left-amount}" 
    ) 
    printMonthly(principal, amount, month+1) 
    } 
}