Created
November 9, 2012 06:50
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Give change with the least amount of coins
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object CoinMachine { | |
def changeWithBigCoin(accum: Change, changeOwing: Double, avaliableChange: Change): (Change, Double, Change) = { | |
if (changeOwing < 0) throw new Error("Cannot give change with existing coins") | |
else if (changeOwing == 0) return (accum, 0, avaliableChange) | |
else if (changeOwing >= 5 && avaliableChange.fiveDollarsLeft > 0) changeWithBigCoin(accum.changeFiveDollar(1), changeOwing - 5, avaliableChange.changeFiveDollar(-1)) | |
else if (changeOwing >= 2 && avaliableChange.twoDollarsLeft > 0) changeWithBigCoin(accum.changeTwoDollar(1), changeOwing - 2, avaliableChange.changeTwoDollar(-1)) | |
else if (changeOwing >= 1 && avaliableChange.dollarsLeft > 0) changeWithBigCoin(accum.changeDollar(1), changeOwing - 1, avaliableChange.changeDollar(-1)) | |
else if (changeOwing >= 0.5 && avaliableChange.fiftycentsLeft > 0) changeWithBigCoin(accum.changeFiftyCent(1), changeOwing - 0.5, avaliableChange.changeFiftyCent(-1)) | |
else throw new Error("Cannot give change on remainder: " + changeOwing) | |
} | |
def pay(paidAmount: Double, cost: Double, availableChange: Change): Change = { | |
val requiredChange: Double = paidAmount - cost | |
if (requiredChange < 0) throw new Error("Pay me more") | |
else if (requiredChange == 0) return new Change(0, 0, 0, 0) | |
else { | |
val result = changeWithBigCoin(new Change(0, 0, 0, 0), requiredChange, availableChange) | |
result._1 | |
} | |
} | |
pay(10, 7, new Change(2, 2, 0, 5)) | |
class Change(fiftycents: Int, dollars: Int, twoDollars: Int, fiveDollars: Int) { | |
def changeFiveDollar(amt: Int) = new Change(fiftycents, dollars, twoDollars, fiveDollars + amt) | |
def changeTwoDollar(amt: Int) = new Change(fiftycents, dollars, twoDollars + amt, fiveDollars) | |
def changeDollar(amt: Int) = new Change(fiftycents, dollars + amt, twoDollars, fiveDollars) | |
def changeFiftyCent(amt: Int) = new Change(fiftycents + amt, dollars, twoDollars, fiveDollars) | |
override def toString() = "(" + fiftycents + ", " + dollars + ", " + twoDollars + ", " + fiveDollars + ")" | |
def fiftycentsLeft = fiftycents; | |
def dollarsLeft = dollars; | |
def twoDollarsLeft = twoDollars; | |
def fiveDollarsLeft = fiveDollars | |
} | |
} |
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