maximal suffix

alib2algo/src/string/properties/MaximalSuffix.cpp

+/*
+ * MaximalSuffix.cpp
+ *
+ *  Created on: 27.3.2020
+ *      Author: Jan Jirak
+ */
+
+#include "MaximalSuffix.h"
+#include <registration/AlgoRegistration.hpp>
+
+namespace {
+
+auto MaxSuffixLinearString = registration::AbstractRegister < string::properties::MaximalSuffix, ext::pair < size_t, size_t >, const string::LinearString < > & > ( string::properties::MaximalSuffix::construct );
+
+} /* namespace */

alib2algo/src/string/properties/MaximalSuffix.h

+/*
+ * MaximalSuffix.h
+ *
+ *  Created on: 27.3.2020
+ *      Author: Jan Jirak
+ */
+
+#ifndef _MAXIMAL_SUFFIX_H_
+#define _MAXIMAL_SUFFIX_H_
+
+#include <alib/vector>
+#include <string/LinearString.h>
+
+namespace string {
+
+namespace properties {
+
+class MaximalSuffix {
+public:
+	/**
+	 * Computes maximal suffix and its period of string
+	 * Inspired be fig.17 in by article Two-way string-matching by Crochemore
+	 * @param string string to compute max suffix for
+	 * @return Pair of starting index of the suffix and lenght of its period
+	 */
+	template < class SymbolType >
+	static ext::pair<size_t, size_t > construct(const string::LinearString < SymbolType >& string);
+
+    /**
+     * Computes maximal suffix and its period of string for reversed alphabet
+     * Inspired be fig.17 in by article Two-way string-matching by Crochemore
+     * @note this is for reversed alphabet
+     * @param string string to compute max suffix for
+     * @return Pair of starting index of the suffix and lenght of its period
+     */
+    template < class SymbolType >
+    static ext::pair<size_t, size_t > constructReversed(const string::LinearString < SymbolType >& string);
+};
+
+template < class SymbolType >
+ext::pair<size_t, size_t > MaximalSuffix::construct(const string::LinearString < SymbolType >& string) {
+	const auto& x = string.getContent();
+	size_t i = 0, j = 1, k = 1, p = 1;
+
+	while (j + k <= x.size()) {
+	    auto A = x[i + k - 1];
+	    auto a = x[j + k - 1];
+	    if ( a < A ) { j = j + k ; k = 1 ; p = j - i ; }
+	    else if ( a == A ) {
+	        if ( k == p ) { j = j + p ; k = 1 ; } else { k = k + 1 ;}
+	    } else { i = j ; j = i + 1 ; k = 1 ; p = 1 ;}
+	}
+	return ext::make_pair( i , p );
+}
+
+template < class SymbolType >
+ext::pair<size_t, size_t > MaximalSuffix::constructReversed(const string::LinearString < SymbolType >& string) {
+    const auto& x = string.getContent();
+    size_t i = 0, j = 1, k = 1, p = 1;
+
+    while (j + k <= x.size()) {
+        auto A = x[i + k - 1];
+        auto a = x[j + k - 1];
+        if ( a > A ) { j = j + k ; k = 1 ; p = j - i ; }
+        else if ( a == A ) {
+            if ( k == p ) { j = j + p ; k = 1 ; } else { k = k + 1 ;}
+        } else { i = j ; j = i + 1 ; k = 1 ; p = 1 ;}
+    }
+    return ext::make_pair( i , p );
+}
+
+} /* namespace properties */
+
+} /* namespace string */
+
+#endif /* _MAXIMAL_SUFFIX_H_ */