From efa5497c85bc46709d1e357570332fc474d6456d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ing=2E=20Radom=C3=ADr=20Pol=C3=A1ch?= <polacrad@fit.cvut.cz>
Date: Sun, 14 Sep 2014 14:27:36 +0200
Subject: [PATCH] FEATURE: cyclic string canonical form in O(n) time and O(n)
space
---
alib2data/makefile | 2 +-
alib2data/src/string/CyclicString.cpp | 41 ++++++++++++++++++++++-----
2 files changed, 35 insertions(+), 8 deletions(-)
diff --git a/alib2data/makefile b/alib2data/makefile
index 57af86af63..f138e3cb54 100644
--- a/alib2data/makefile
+++ b/alib2data/makefile
@@ -2,7 +2,7 @@ SHELL:=/bin/bash
LIBRARY:=libalib2data.so
TESTBIN:=alib2test
-LDFLAGS:= /usr/lib64/libbfd.a /usr/lib64/libiberty.a -lz -ldl -rdynamic -shared -lxml2
+LDFLAGS:=-lbfd -liberty -lz -ldl -rdynamic -shared -lxml2
TEST_LDFLAGS:= -L../alib2data/lib -rdynamic -lxml2 -lalib2data -lcppunit -Wl,-rpath,.
OBJECTS:=$(patsubst src/%.cpp, obj/%.o, $(shell find src/ -name *cpp))
diff --git a/alib2data/src/string/CyclicString.cpp b/alib2data/src/string/CyclicString.cpp
index dccd4fad7f..fcf1fc8e58 100644
--- a/alib2data/src/string/CyclicString.cpp
+++ b/alib2data/src/string/CyclicString.cpp
@@ -83,13 +83,40 @@ void CyclicString::setContent(std::vector<alphabet::Symbol> data) {
if(unknownSymbols.size() > 0)
throw exception::AlibException("Input symbols not in the alphabet.");
- m_Data = data;
- for(unsigned i = 1; i < data.size(); i++) {
- data.push_back(std::move(data[0]));
- data.erase(data.begin());
-
- if(m_Data > data) m_Data = data;
- }
+ /**
+ * Lexicographically least circular substrings
+ * Kellogg S. Booth
+ * 1979
+ */
+ int* f = new int[data.size()]; /** Knuth–Morris–Pratt like array */
+ int k = 0; /** Least circular string shift value */
+ int i;
+ f[0]=-1;
+ for (unsigned j = 1; j < 2*data.size(); ++j) {
+ /** condition adjusted by RadomĂr Polách, >= is not correct */
+ if (j - k > data.size()) break;
+ i = f[j - k -1];
+ while (data[j % data.size()] != data[(k + i + 1) % data.size()] && i != -1) {
+ if (data[j % data.size()] < data[(k + i + 1) % data.size()]) k = j - i - 1;
+ i = f[i];
+ }
+ if (data[j % data.size()] != data[(k + i + 1) % data.size()] && i == -1) {
+ if (data[j % data.size()] < data[(k + i + 1) % data.size()]) k = j;
+ f[j - k] = -1;
+ } else f[j - k] = i+1;
+ }
+ delete [] f;
+
+ if (k == 0) {
+ m_Data = data;
+ return;
+ }
+
+ std::vector<alphabet::Symbol> tmp;
+ for (unsigned l = k; l < data.size() + k; ++l) {
+ tmp.push_back(std::move(data[l % data.size()]));
+ }
+ m_Data = tmp;
}
bool CyclicString::isEmpty() const {
--
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