C#版后缀树 最长公共串 LCS

看了一些网上的关于后缀树的文章，发现大多是C/C++版的，参照几个版本拼了一个C#版的。

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace test_file{    class fix    {        private void swap(ref int[] x, ref int[] y)        {            int[] temp = x;            x = y;            y = x;        }        const int  MAXN = 500005;        //using namespace std;        int[] r = new int[MAXN];        int[] wa = new int[MAXN];        int[] wb = new int[MAXN];        int[] wv = new int[MAXN];        int[] tmp = new int[MAXN];        int[]sa = new int[MAXN];                private bool cmp(int [] r, int a, int b, int l)        {            return r[a] == r[b] && r[a + l] == r[b + l];        }        /// <summary>        ///         /// </summary>        /// <param name="r"></param>        /// <param name="sa">与r类型、长度相同的数组</param>        /// <param name="n">为数组r的长度</param>        /// <param name="m">数组中的最大值加1</param>        public  void da(int []r, int []sa, int n, int m)        {            int i, j, p;            int  [] x = wa; int [] y = wb ; int []ws = tmp;            int[] t;            for (i = 0; i < m; i++) ws[i] = 0;            for (i = 0; i < n; i++) ws[x[i] = r[i]]++;            for (i = 1; i < m; i++) ws[i] += ws[i - 1];            for (i = n - 1; i >= 0; i--)sa[--ws[x[i]]] = i;            for (j = 1, p = 1; p < n; j *= 2, m = p)     // 对长度为2的K次幂的前缀进行排序 求出rank值            {                for (p = 0, i = n - j; i < n; i++)y[p++] = i;                for (i = 0; i < n; i++)if (sa[i] >= j) y[p++] = sa[i] - j;                for (i = 0; i < n; i++) wv[i] = x[y[i]];                for (i = 0; i < m; i++) ws[i] = 0;                for (i = 0; i < n; i++) ws[wv[i]]++;                for (i = 1; i < m; i++) ws[i] += ws[i - 1];                for (i = n - 1; i >= 0; i--) sa[--ws[wv[i]]] = y[i];                for (t = x, x = y, y = t, p = 1, x[sa[0]] = 0, i = 1; i < n; i++)                    x[sa[i]] = cmp(y, sa[i - 1], sa[i], j) ? p - 1 : p++;            }        }        int [] rank = new int [MAXN];        private int [] height = new int[MAXN];        public void calheight(int [] r,int []sa,int n)        {             int i,j,k=0;             for(i=1;i<=n;i++)          rank[sa[i]]=i;             for(i=0;i<n;height[rank[i++]]=k)                        {                  if(k > 0) k--;                 else k = 0;                 for(j = sa[rank[i] -1]; r[i+k] == r[j+k] ; k++);             }             return;        }            int[] belong = new int[MAXN];        int VISIT_LEN = 5000;        private  bool ok(int A,int n, int m ,int [] sa)        {            int i,j,k;        bool []  ba = new bool [VISIT_LEN];        for (i=1;i<=n;i++)        {        if (height[i]>=A)        {        for (j=i;height[j]>=A && j<=n;j++);        j--;                    for (int nd = 0; nd < VISIT_LEN; nd++)                    {                        ba[nd] = false;                    }        for (k=i-1;k<=j;k++)        ba[belong[sa[k]]]=true;        for (k=0;ba[k] && k<n;k++);        if (k==m)        return true;        i=j;        }        }        return false;        }        /// <summary>        /// 二分搜索        /// </summary>        /// <param name="n">拼接后的字符串长度</param>        /// <param name="m">拼接前的字符串个数</param>        /// <param name="arr">初始字符串数组</param>        /// <returns></returns>        private int binarySearch(int n , int m,int []arr)        {            int l = 0, r = n;            int mid;            while (l +1 < r)            {                mid = (l + r)/2;                if (ok(mid,n,m,arr))                    l = mid;                else r = mid - 1;            }            if (ok(r, n, m, arr))                l = r;            return l;        }        /// <summary>        /// 获取最长公共前缀        /// </summary>        /// <param name="str">字符串数组</param>        /// <returns></returns>        public string  get_LCS(string[] str)        {                       string ss = null;            //int str_max_length = 0;            int mark = 0; int char_len = 0;            foreach (string s in str)            {                ss += s;                char[] temp = s.ToCharArray();                for(int i = 0 ; i < temp.Length ; i++)                {                    belong[char_len++] = mark;                }                char_len++;                ss += (char)(0xFD9B + (mark++)); //字符串之间用一个没有出现过的字符间隔。 （str1 * str2 * str 3 * .....* strn *）   *为不同的符号            }            int m = 0, n = ss.Length;            int[] r = new int[ss.Length + 1];            int[] saa = new int[ss.Length + 1];            char[] chars = ss.ToCharArray();                        for (int i = 0; i < chars.Length; i++)            {                r[i] = (int)chars[i];                m = m > (int)chars[i] ? m : (int)chars[i];            }            r[n] = 0;            da(r, saa, n + 1, m + 1);            calheight(r, saa, ss.Length);            int resu = binarySearch(ss.Length, mark,saa);            if(resu > 0)              return get_ndx(resu , n ,  str.Length , chars,saa);            else              return "none";        }        /// <summary>        /// 返回最长公共字符串        /// </summary>        /// <param name="len">最长字符串长度</param>        /// <param name="n">拼接后的字符串长度</param>        /// <param name="m">初始字符串数组中字符串的个数</param>        /// <param name="s">拼接并转换后的字符数组</param>        /// <param name="sa">sa数组，保存的是“排第几的是谁”</param>        /// <returns></returns>        private string get_ndx(int len , int n , int m , char [] s,int [] sa)        {            //outset.clear();            StringBuilder result = new StringBuilder();            bool[] visit = new bool[VISIT_LEN];            int count=0;            for(int i=1;i<n;i++)            {                if(height[i+1]<len)                {                    if(count>0)                    {                        if(count>m/2)                        {                            for(int j=0,index=sa[i];j<len;j++)                                result.Append(s[j+index]);                            result.Append("α");                         }                        count=0;                        for (int ii = 0; ii < VISIT_LEN; ii++)                        {                            visit[ii] = false;                        }                    }                }                else                {                    if(!visit[belong[sa[i]]])                    {                        visit[belong[sa[i]]]=true ;                        count++;                    }                    if(!visit[belong[sa[i+1]]])                    {                        visit[belong[sa[i+1]]]=true;                        count++;                    }                }            }            return result.ToString();        }    }}