kotlin实现罗马数字和阿拉伯数字转换

最新推荐文章于 2019-09-25 10:50:04 发布

原创最新推荐文章于 2019-09-25 10:50:04 发布 · 1.3k 阅读

0 ·

CC 4.0 BY-SA版权

kotlin 专栏收录该内容

1 篇文章

订阅专栏

本文介绍了如何使用Kotlin进行罗马数字与阿拉伯数字的转换。首先，详细阐述了罗马数字转阿拉伯数字的过程，通过遍历罗马数字的每一位并比较大小来计算结果。接着，讨论了阿拉伯数字转罗马数字的方法，通过建立映射关系，判断当前数字与罗马数字对应值的关系来构建转换结果。

1.罗马数字转阿拉伯数字

遍历罗马数字的每一位，若当前位比前一位小，则在结果中加上当前位

否则在结果中减去前一位的两倍再加上当前位

2.阿拉伯数字转罗马数字

先构造map

mapOf(1000 to "M",900 to "CM",500 to "D",400 to "CD",100 to "C",90 to "XC",50 to "L",40 to "XL",10 to "X",9 to "IX",5 to "V",4 to "IV",1 to "I")

遍历map

若当前数字大于第i个数字

将第i个数字对应的字母加入结果中，当前数字－＝第i个数字

val romeChar=mapOf(
        'I' to 1,
        'V' to 5,
        'X' to 10,
        'L' to 50,
        'C' to 100,
        'D' to 500,
        'M' to 1000
)


class RomeNumber private constructor(){
    constructor(number:String):this(){
        this.number=number
    }
    var number:String=""
        set(value){
            if(value.toCharList().any{!romeChar.containsKey(it)}) throw object :Exception("It is not a legal Rome Number"){ } else $number=value.toUpperCase()
        }
    public fun toArabicNumber():Int{
        var lastNumber=0
        var sum=0
        number.toCharList().forEach {
            var value:Int?=romeChar.get(it)
            if (value!!>lastNumber) {sum-=lastNumber*2;sum+=value;}else sum+=value
            lastNumber=value
        }
        return sum
    }

    override fun toString(): String {
        return number
    }
}


fun Int.toRomeNumber():RomeNumber{
    val additionMap = mapOf(1000 to "M",900 to "CM",500 to "D",400 to "CD",100 to "C",90 to "XC",50 to "L",40 to "XL",10 to "X",9 to "IX",5 to "V",4 to "IV",1 to "I")
    val sb=StringBuilder()
    var temp=this
    while (temp != 0) {
        additionMap.forEach {
            while (temp >= it.getKey()) {
                sb.append(it.getValue())
                temp -= it.getKey()
            }
        }
    }
    return RomeNumber(sb.toString())
}