Lab 7

README.md

@@ -1,24 +1,4 @@
-# Lab-1 
+# Lab 7 - Dynamic Programming
 
-## Task
-Implement a sorting algorithm - HeapSort(ascending/descending)
+### Rabin Karp String Matching Algorithm
 
-## Result output
-- Algorithm's name
-- Execution time
-- Counters: swaps, comparisons
-- Sorting result
-
-## Code must be covered with tests
-- sort the input array
-- sort in ascending order of sorted array in ascending order
-- sort in descending order of sorted array in ascending order
-- sort in ascending order of sorted array in descending order
-- sort in descending order of sorted array in descending order
-
-## How to run
-- 'cd' into folder where you want to store this repository
-- Clone this repository with command 'git clone https://github.com/yeldmitrenko/Algorithms_Labs.git'
-- Choose branch lab_1 with command 'git checkout lab_1'
-- Go into folder with files with command 'cd Algorithms_Labs'
-- run command 'python main.py'

rabin_karp.py

@@ -0,0 +1,46 @@
+alphabet_size = 256
+
+
+def calculate_hash(pattern, primary_number):
+    reducing_hash_number = 1
+
+    for i in range(len(pattern) - 1):
+        reducing_hash_number = (reducing_hash_number * alphabet_size) % primary_number
+
+    return reducing_hash_number
+
+
+def rabin_karp_search(text, pattern, primary_number=101):
+    positions_array = []
+    text_hash_value = 0
+    pattern_hash_value = 0
+
+    reducing_hash_number = calculate_hash(pattern, primary_number)
+
+    for i in range(len(pattern)):
+        text_hash_value = (alphabet_size * text_hash_value + ord(text[i])) % primary_number
+        pattern_hash_value = (alphabet_size * pattern_hash_value + ord(pattern[i])) % primary_number
+
+    for i in range(len(text) - len(pattern) + 1):
+        if pattern_hash_value == text_hash_value:
+            matches_number = 0
+            for j in range(len(pattern)):
+                if pattern[j] == text[j + i]:
+                    matches_number += 1
+                else:
+                    break
+            if matches_number == len(pattern):
+                positions_array.append(i)
+
+        if i < len(text) - len(pattern):
+            text_hash_value = (alphabet_size * (text_hash_value - ord(text[i]) * reducing_hash_number) + ord(
+                text[i + len(pattern)])) % primary_number
+            text_hash_value = text_hash_value + primary_number if text_hash_value < 0 else text_hash_value
+    return positions_array
+
+
+if __name__ == '__main__':
+    text = "BBCLLNMNLLN"
+    pattern = "LLN"
+
+    print(rabin_karp_search(text, pattern))

test.py

@@ -1,28 +1,26 @@
 import unittest
-from heap_sort import heap_sort
-from copy import deepcopy
 
+from lab7.rabin_karp import rabin_karp_search
 
-class TestHeapSort(unittest.TestCase):
-    def setUp(self) -> None:
-        self.array_example = [1, 2, 56, 45, -9, 78, 11]
-        self.array_sorted_asc = [-9, 1, 2, 11, 45, 56, 78]
-        self.array_sorted_desc = [78, 56, 45, 11, 2, 1, -9]
 
-    def test_sort_asc(self):
-        self.assertListEqual(heap_sort(deepcopy(self.array_example), "asc"), self.array_sorted_asc)
+class RabinKarpTest(unittest.TestCase):
+    def setUp(self) -> None:
+        self.test_text1 = "AAA NN MM LL K AA"
+        self.test_pattern1 = "AA"
+        self.benchmark_positions_array1 = [0, 1, 15]
 
-    def test_sort_desc(self):
-        self.assertListEqual(heap_sort(deepcopy(self.array_example), "desc"), self.array_sorted_desc)
+        self.test_pattern2 = "LLN"
+        self.test_text2 = "BBCLLNMNLLN"
+        self.benchmark_positions_array2 = [3, 8]
 
-    def test_sort_asc_in_asc(self):
-        self.assertListEqual(heap_sort(deepcopy(self.array_sorted_asc), "asc"), self.array_sorted_asc)
+    def test_rabin_karp_search_1(self):
+        pattern_positions = rabin_karp_search(self.test_text1, self.test_pattern1)
+        self.assertEqual(pattern_positions, self.benchmark_positions_array1)
 
-    def test_sort_asc_in_desc(self):
-        self.assertListEqual(heap_sort(deepcopy(self.array_sorted_asc), "desc"), self.array_sorted_desc)
+    def test_rabin_karp_search_2(self):
+        pattern_positions = rabin_karp_search(self.test_text2, self.test_pattern2)
+        self.assertEqual(pattern_positions, self.benchmark_positions_array2)
 
-    def test_sort_desc_in_asc(self):
-        self.assertListEqual(heap_sort(deepcopy(self.array_sorted_desc), "asc"), self.array_sorted_asc)
 
-    def test_sort_desc_in_desc(self):
-        self.assertListEqual(heap_sort(deepcopy(self.array_sorted_desc), "desc"), self.array_sorted_desc)
+if __name__ == '__main__':
+    unittest.main()