public static long[] PreComputeHashes(
string T,
int P,
long p,
long x
)
{
int textLength = T.Length;
long[] hashes = new long[textLength - P + 1];
hashes[T.Length - P] = HashingWithChain.PolyHash(
T, start: textLength - P, count: P, p: p, x: x);
long y = 1;
for (int i = 1; i <= P; i++)
{
y = (y * x) % p;
}
for (int i = textLength - P - 1; i >= 0; i--)
{
hashes[i] = (((x * hashes[i + 1]) + T[i] - (y * T[i + P])) % p + p) % p;
}
return(hashes);
}
static void Main(string[] args)
{
HashingWithChain a = new HashingWithChain("TD2");
a.Solve(5, new string[] { "add test", "add test", "find test", "check 0",
"check 1", "check 2", "check 3", "check 4",
"del test", "del test", "find test", "find Test", "add Test", "find Test" });
}
public long[] Solve(string pattern, string text)
{
List <long> occurrences = new List <long>();
long hash = HashingWithChain.PolyHash(pattern, 0, pattern.Length);
var textHashes = PreComputeHashes(text, pattern.Length);
for (long i = 0; i < textHashes.Length; i++)
{
if (hash == textHashes[i] && pattern == text.Substring((int)i, pattern.Length))
{
occurrences.Add(i);
}
}
return(occurrences.ToArray());
}
public static long[] PreComputeHashes(
string T,
int len,
long p = BigPrimeNumber,
long x = ChosenX)
{
long xp = HashingWithChain.Pow(x, len, p);
long[] result = new long[T.Length - len + 1];
result[T.Length - len] = HashingWithChain.PolyHash(T, T.Length - len, len, (int)p, p, x);
for (int i = T.Length - len - 1; i >= 0; i--)
{
result[i] = ((x * result[i + 1] + T[i] - T[i + len] * xp % p) % p + p) % p;
}
return(result);
}
public static long[] PreComputeHashes(
string T,
int P,
long p = BigPrimeNumber,
long x = ChosenX)
{
long[] preComHashes = new long[T.Length - P + 1];
preComHashes[T.Length - P] = HashingWithChain.PolyHash(T, T.Length - P, P, p, p, x);
long y = HashingWithChain.Power(x, P);
for (int i = T.Length - P - 1; i >= 0; i--)
{
preComHashes[i] = ((x * preComHashes[i + 1] + T[i] - y * T[i + P] % p) % p + p) % p;
}
return(preComHashes);
}
public long[] Solve(string pattern, string text)
{
List <long> occurrences = new List <long>();
long[] preComputeHashes = PreComputeHashes(text, pattern.Length);
long patternHash = HashingWithChain.PolyHash(pattern, 0, pattern.Length);
for (int i = 0; i <= text.Length - pattern.Length; i++)
{
if (preComputeHashes[i] != patternHash)
{
continue;
}
else if (pattern == text.Substring(i, pattern.Length))
{
occurrences.Add(i);
}
}
return(occurrences.ToArray());
}
public long[] Solve(string pattern, string text)
{
Random r = new Random();
long x = r.Next(1, (int)BigPrimeNumber - 1);
List <long> occurrences = new List <long>();
long pHash = HashingWithChain.PolyHash(pattern, 0, pattern.Length, x: x);
long[] tHashes = PreComputeHashes(text, pattern.Length, BigPrimeNumber, x);
for (int i = 0; i <= text.Length - pattern.Length; i++)
{
if (pHash == tHashes[i])
{
if (pattern.Equals(text.Substring(i, pattern.Length)))
{
occurrences.Add(i);
}
}
}
return(occurrences.ToArray());
}
