Merge pull request #5 from sandyre/algorithm-dev

KMP algorithm

Author: Blinkop

include/cslib/algorithm/search/kmp_search.hpp

@@ -0,0 +1,80 @@
+#ifndef CSLIB_ALGORITHM_SEARCH_KMP_SEARCH_HPP
+#define CSLIB_ALGORITHM_SEARCH_KMP_SEARCH_HPP
+
+// MIT License
+//
+// Copyright (c) 2018 Alexandr Borzykh
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+#include <cslib/data_structure/dynamic_array.hpp>
+
+#include <iterator>
+
+namespace cslib {
+namespace algorithm
+{
+
+	/* Name: Knuth-Morris-Pratt searching algorithm
+	 * Runtime complexity: O(n)
+	 * Space complexity: O(m), where m is pattern
+	 *
+	 * Interesting fact: it's widely used with strings, but implementation is generic and can work with basically all containers and types (contained type must have operator==)
+	 */
+
+	template < typename IteratorT >
+	IteratorT kmp_search(IteratorT begin, IteratorT end, IteratorT pattern_begin, IteratorT pattern_end)
+	{
+		using iterator_traits = std::iterator_traits<IteratorT>;
+
+		const typename iterator_traits::difference_type source_length = std::distance(begin, end), pattern_length = std::distance(pattern_begin, pattern_end);
+		data_structure::dynamic_array<uint32_t> prefix_func(pattern_length, 0);
+
+		uint32_t k;
+		IteratorT pattern_iter;
+		for (k = 0, pattern_iter = pattern_begin; pattern_iter != pattern_end; ++pattern_iter)
+		{
+			while ((k > 0) && (*pattern_iter != *(pattern_begin + k)))
+				k = prefix_func[k - 1];
+
+			if (*pattern_iter == *(pattern_begin + k))
+				++k;
+
+			prefix_func[std::distance(pattern_begin, pattern_iter)] = k;
+		}
+
+		IteratorT source_iter;
+		for (k = 0, source_iter = begin; source_iter != end; ++source_iter)
+		{
+			while ((k > 0) && (*(pattern_begin + k) != *source_iter))
+				k = prefix_func[k - 1];
+
+			if (*(pattern_begin + k) == *source_iter)
+				++k;
+
+			if (k == pattern_length)
+				return source_iter - pattern_length + 1;
+		}
+
+		return end;
+	}
+
+}}
+
+#endif

include/cslib/data_structure/dynamic_array.hpp

@@ -144,7 +144,7 @@ namespace data_structure
 		:	_data(std::allocator_traits<allocator>::allocate(_allocator, initial_size)),
 			_capacity(initial_size),
 			_size(initial_size)
-	{ algorithm::for_each_iterator(begin(), end(), std::bind(&std::allocator_traits<allocator>::construct, std::ref(_allocator), std::placeholders::_1, filler)); }
+	{ algorithm::for_each_iterator(begin(), end(), [&](pointer ptr) { std::allocator_traits<allocator>::construct(_allocator, ptr, filler); }); }
 
 
 	template < typename ValueT >

tests/CMakeLists.txt

@@ -3,6 +3,7 @@ option(BUILD_TESTS "Build unit tests" OFF)
 SET(SOURCES
 	algorithm/binary_search.cpp
 	algorithm/linear_search.cpp
+	algorithm/kmp_search.cpp
 
 	algorithm/insertion_sort.cpp
 	algorithm/maximum_subarray.cpp

tests/algorithm/kmp_search.cpp

@@ -0,0 +1,25 @@
+#include <gtest/gtest.h>
+
+#include <cslib/algorithm/search/kmp_search.hpp>
+
+#include <vector>
+
+template <typename T>
+using DefaultContainer = std::vector<T>;
+
+TEST(kmp_search, empty_input)
+{
+	DefaultContainer<int> container;
+	DefaultContainer<int> pattern { 5 };
+
+	ASSERT_EQ(cslib::algorithm::kmp_search(container.begin(), container.end(), pattern.begin(), pattern.end()), container.end());
+}
+
+
+TEST(kmp_search, simple_input)
+{
+	DefaultContainer<int> container { 0, 10, 5, 4, 3 };
+	DefaultContainer<int> pattern { 5, 4, 3 };
+
+	ASSERT_EQ(cslib::algorithm::kmp_search(container.begin(), container.end(), pattern.begin(), pattern.end()), container.begin() + 2);
+}