12.Integer_to_Roman.kt

//time complexity:O(n), space: O(n)
fun intToRoman(num: Int): String {
    val 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"
    )
    var result = ""
    var n = num
    for ((value, symbol) in map) {
        while (n >= value) {
            n -= value
            result += symbol
        }
    }
    return result
}