using System;  
    using System.Collections.Generic;  
    using System.Linq;  
    using System.Text;  
      
    namespace Viterbi  
    {  
        class Program  
        {  
            const int m = 2;  //隐含状态数  
            const int n = 3;  //观察状态数  
            static int[] sArray = new int[n];  //隐含状态序列  
            static int[] oArray = { 0, 1, 2 };  //可观察状态序列  
            static double[] iArray = { 0.6, 0.4 };//初始概率矩阵  
            static double[,] aArray = { { 0.7, 0.3 }, { 0.4, 0.6 } };//转移概率矩阵  
            static double[,] bArray = { { 0.5, 0.4, 0.1 }, { 0.1, 0.3, 0.6 } };//发射概率矩阵  
            static double[,] resultArray = new double[n, m];//保存结果   
      
            static void Main(string[] args)  
            {  
                Viterbi(sArray, oArray, iArray, aArray, bArray);  
                foreach (int i in sArray)  
                {  
                    Console.Write(i);  
                }  
                Console.ReadKey();  
            }  
      
            static void Viterbi(int[] s, int[] o, double[] i, double[,] a, double[,] b)  
            {  
                for (int j = 0; j < m; j++)  
                {  
                    resultArray[0, j] = iArray[j] * bArray[j, oArray[0]];  
                }  
                for (int j = 1; j < n; j++)  
                {  
                    for (int p = 0; p < m; p++)  
                    {  
                        for (int k = 0; k < m; k++)  
                        {  
                            double tmp = resultArray[j - 1, p] * aArray[p, k] * bArray[k, oArray[j]];  
                            if (tmp > resultArray[j, k])  
                                resultArray[j, k] = tmp;  
                        }  
                    }  
                }  
                for (int j = 0; j < n; j++)  
                {  
                    double tmp = resultArray[j, 0];  
                    sArray[j] = 0;  
                    for (int p = 0; p < m; p++)  
                    {  
                        if (resultArray[j, p] > tmp)  
                            sArray[j] = p;  
                    }  
                }  
            }  
        }  
    }