阿拉伯数字转为罗马数字(记录)

using System.Collections;
using System.Collections.Generic;
using UnityEngine;



/*Write Date:20230425
 rome name  ：https://b2b.partcommunity.com/community/knowledge/zh_CN/detail/10753/%E7%BD%97%E9%A9%AC%E6%95%B0%E5%AD%97#knowledge_article
     */
public class RomeNumberConvert
{
    #region 罗马数字转为阿拉伯数字
    /// 

    /// 罗马数字转为阿拉伯数字
    /// 
    /// "CII"
    /// 
    public static int RomeNumberToArabic(string s)
    {
        s = s.Replace("IV", "a");
        s = s.Replace("IX", "b");
        s = s.Replace("XL", "c");
        s = s.Replace("XC", "d");
        s = s.Replace("CD", "e");
        s = s.Replace("CM", "f");

        int result = 0;
        for (int i = 0; i < s.Length; i++)
        {
            result += WhichArabic(s[i]);
        }
        return result;
    }

    private static int WhichArabic(char ch)
    {
        switch (ch)
        {
            case 'I': return 1;
            case 'V': return 5;
            case 'X': return 10;
            case 'L': return 50;
            case 'C': return 100;
            case 'D': return 500;
            case 'M': return 1000;
            case 'a': return 4;
            case 'b': return 9;
            case 'c': return 40;
            case 'd': return 90;
            case 'e': return 400;
            case 'f': return 900;
        }
        return 0;
    } 
    #endregion

    #region 阿拉伯数字转为罗马数字
    static int[] luomaSign = new int[13] { 1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 };
    /// 

    /// 阿拉伯数字转为罗马数字
    /// 
    /// [1,4000)
    /// 
    public static string ArabicNumberToRome(int val)
    {
        string luoma = "";
        //int signIndex = 0;
        while (val > 0)
        {
            //换成这样查找可能省点0.0
            int signNum = GetSign(val);
            if (val >= signNum)
            {
                val -= signNum;
                luoma += WhichRome(signNum);
            }
            
            //if (signIndex < luomaSign.Length)
            //{
            //    int signNum = luomaSign[signIndex];
            //    if (val >= signNum)
            //    {
            //        val -= signNum;
            //        luoma += WhichRome(signNum);
            //    }
            //    if (val < signNum)
            //    {
            //        signIndex += 1;
            //    }
            //}
        }
        return luoma;
    }

    private static string WhichRome(int val)
    {
        switch (val)
        {
            case 1: return "I";
            case 5: return "V";
            case 10: return "X";
            case 50: return "L";
            case 100: return "C";
            case 500: return "D";
            case 1000: return "M";
            case 4: return "IV";
            case 9: return "IX";
            case 40: return "XL";
            case 90: return "XC";
            case 400: return "CD";
            case 900: return "CM";
        }
        return "";
    }

    private static int GetSign(int target)
    {
        int signIndex = FindFitSign(luomaSign, target);
        signIndex = Mathf.Clamp(signIndex, 0, luomaSign.Length - 1);
        return luomaSign[signIndex];

    }

    static int FindFitSign(int[] nums, int target)
    {
        if (nums == null || nums.Length == 0)
            return -1;

        int left = 0, right = nums.Length - 1;
        while (left + 1 < right)
        {
            // Prevent (left + right) overflow
            int mid = left + (right - left) / 2;
            if (nums[mid] == target)
            {
                return mid;
            }
            else if (nums[mid] > target)
            {
                left = mid;
            }
            else
            {
                right = mid;
            }
        }

        if (target >= nums[left])
        {
            return left;
        }
        if (target >= nums[right])
        {
            return right;
        }
        return -1;
    }
    #endregion
}

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