/*
* Pattern Matching Algorithms with Don’t Cares
* Costas S. Iliopoulos and M. Sohel Rahman
* Algorithm Design Group
* Department of Computer Science, King’s College London
*/
/// </summary>
/// Given a text T over the alphabet Σ and a pattern P
/// over the alphabet Σ∪{∗}, find all the occurrences of
/// P in T.
/// <param name="T"></param>
/// <param name="P"></param>
public IEnumerable <int> FindDcp(string T, string P)
{
var sa = new SuffixArray <char>(T.ToCharArray());
int[] permitted = new int[T.Length];
Tuple <string[], int[]> pat = splitPattern(P);
var l = pat.Item1.Length;
var Val = new int[l];
Val[0] = 0;
for (int i = 1; i < l; ++i)
{
Val[i] = Val[i - 1] + pat.Item1[i - 1].Length + pat.Item2[i - 1];
}
var occ_P = new SortedSet <int>();
for (int i = 0; i < l; ++i)
{
var Pi = pat.Item1[i];
var occ_Pi = new SortedSet <int>(sa.FindOccurences(Pi.ToCharArray()));
foreach (var r in occ_Pi)
{
++permitted[r - Val[i]];
if (permitted[r - Val[i]] == l)
{
occ_P.Add(r - Val[i]);
}
}
}
return(occ_P);
}
public IEnumerable <int> FindIdcp(string T, string P)
{
var sa = new SuffixArray <char>(T.ToCharArray());
Tuple <string[], int[]> pat = splitPattern(P);
var l = pat.Item1.Length;
var Val = new int[l];
Val[0] = 0;
for (int i = 1; i < l; ++i)
{
Val[i] = Val[i - 1] + pat.Item1[i - 1].Length + pat.Item2[i - 1];
}
var occ_P = new SortedSet <int>();
var P_1 = pat.Item1[0];
var occ_P1 = sa.FindOccurences(P_1.ToCharArray());
var permitted = occ_P1.ToDictionary(i => i, v => 1);
for (int i = 0; i < l; ++i)
{
var Pi = pat.Item1[i];
var occ_Pi = sa.FindOccurences(Pi.ToCharArray());
foreach (var r in occ_Pi)
{
int r_val = r - Val[i];
int c;
if (permitted.TryGetValue(r_val, out c))
{
++c;
permitted[r_val] = c;
if (c == l)
{
occ_P.Add(r_val);
}
}
}
}
return(occ_P);
}
