From dc979e7c5a0b9393165de47da8564a8c2d208eb6 Mon Sep 17 00:00:00 2001
From: Jan Travnicek <Jan.Travnicek@fit.cvut.cz>
Date: Wed, 21 Dec 2016 20:13:41 +0100
Subject: [PATCH] fix finding least lexicographical rotation
---
.../src/string/simplify/NormalizeRotation.cpp | 19 +++++++++----------
.../test-src/string/compare/compareTest.cpp | 7 ++++++-
2 files changed, 15 insertions(+), 11 deletions(-)
diff --git a/alib2algo/src/string/simplify/NormalizeRotation.cpp b/alib2algo/src/string/simplify/NormalizeRotation.cpp
index a2d3adc831..b8b9c35043 100644
--- a/alib2algo/src/string/simplify/NormalizeRotation.cpp
+++ b/alib2algo/src/string/simplify/NormalizeRotation.cpp
@@ -19,24 +19,23 @@ string::String NormalizeRotation::normalize(const string::String& string) {
string::CyclicString < > NormalizeRotation::normalize(const string::CyclicString < >& string) {
/**
- * Lexicographically least circular substrings
+ * Lexicographically least circular substrings,
+ * based on
* Kellogg S. Booth
- * 1979
+ * 1979,
+ * modified to working code by Ladislav Vagner
*/
const std::vector<alphabet::Symbol>& data = string.getContent();
- int* f = new int[data.size() + 1]; /** Knuth–Morris–Pratt like array */
+ int* f = new int[ 2 * 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 Radomir Polach, >= 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) {
+ int i = f[j - k - 1];
+ while ( i != -1 && data[j % data.size()] != data[(k + i + 1) % data.size()]) {
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 (i == -1 && data[j % data.size()] != data[k % data.size()]) {
if (data[j % data.size()] < data[(k + i + 1) % data.size()]) k = j;
f[j - k] = -1;
} else f[j - k] = i + 1;
@@ -47,7 +46,7 @@ string::CyclicString < > NormalizeRotation::normalize(const string::CyclicString
return string;
std::vector<alphabet::Symbol> rotated;
- for (unsigned l = k; l < data.size() + k; ++l) {
+ for (unsigned l = k % data.size ( ); l < data.size() + k % data.size ( ); ++l) {
rotated.push_back(data[l % data.size()]);
}
diff --git a/alib2algo/test-src/string/compare/compareTest.cpp b/alib2algo/test-src/string/compare/compareTest.cpp
index 2606492375..b380ec5a43 100644
--- a/alib2algo/test-src/string/compare/compareTest.cpp
+++ b/alib2algo/test-src/string/compare/compareTest.cpp
@@ -56,7 +56,7 @@ void compareTest::testCompareCyclic() {
string::CyclicString < > cyclic3n = string::simplify::NormalizeRotation::normalize(cyclic3);
string::CyclicString < > cyclic4n = string::simplify::NormalizeRotation::normalize(cyclic4);
-
+ CPPUNIT_ASSERT(cyclic1 == cyclic1n);
CPPUNIT_ASSERT(cyclic1n == cyclic2n);
CPPUNIT_ASSERT(cyclic1n == cyclic3n);
CPPUNIT_ASSERT(cyclic2n == cyclic3n);
@@ -64,5 +64,10 @@ void compareTest::testCompareCyclic() {
CPPUNIT_ASSERT(cyclic4n != cyclic1n);
CPPUNIT_ASSERT(cyclic4n != cyclic2n);
CPPUNIT_ASSERT(cyclic4n != cyclic3n);
+
+ string::CyclicString < > cyclic5({alphabet::Symbol(62), alphabet::Symbol(62), alphabet::Symbol(100), alphabet::Symbol(62)});
+ string::CyclicString < > cyclic5n = string::simplify::NormalizeRotation::normalize(cyclic5);
+ string::CyclicString < > cyclic5r({alphabet::Symbol(62), alphabet::Symbol(62), alphabet::Symbol(62), alphabet::Symbol(100)});
+ CPPUNIT_ASSERT(cyclic5n == cyclic5r);
}
--
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