Interpolation search - fix endless loop bug, divide 0 bug and update description (#793)

* fix endless loop bug, divide 0 bug and update description

fix an endless bug, for example, if collection = [10,30,40,45,50,66,77,93], item = 67.

fix divide 0 bug,  when right=left it is not OK to point = left + ((item - sorted_collection[left]) * (right - left)) // (sorted_collection[right] - sorted_collection[left])

update 'sorted' to 'ascending sorted' in description to avoid confusion

* delete swap files

* delete 'address' and add input validation

searches/test_interpolation_search.py

@@ -0,0 +1,93 @@
+import unittest
+from interpolation_search import interpolation_search, interpolation_search_by_recursion
+
+class Test_interpolation_search(unittest.TestCase):
+    def setUp(self):
+        # un-sorted case
+        self.collection1 = [5,3,4,6,7]
+        self.item1 = 4
+        # sorted case, result exists
+        self.collection2 = [10,30,40,45,50,66,77,93]
+        self.item2 = 66
+        # sorted case, result doesn't exist
+        self.collection3 = [10,30,40,45,50,66,77,93]
+        self.item3 = 67
+        # equal elements case, result exists
+        self.collection4 = [10,10,10,10,10]
+        self.item4 = 10
+        # equal elements case, result doesn't exist
+        self.collection5 = [10,10,10,10,10]
+        self.item5 = 3
+        # 1 element case, result exists
+        self.collection6 = [10]
+        self.item6 = 10
+        # 1 element case, result doesn't exists
+        self.collection7 = [10]
+        self.item7 = 1
+
+    def tearDown(self):
+        pass
+
+    def test_interpolation_search(self):
+        self.assertEqual(interpolation_search(self.collection1, self.item1), None)
+        
+        self.assertEqual(interpolation_search(self.collection2, self.item2), self.collection2.index(self.item2))
+        
+        self.assertEqual(interpolation_search(self.collection3, self.item3), None)
+        
+        self.assertEqual(interpolation_search(self.collection4, self.item4), self.collection4.index(self.item4))
+
+        self.assertEqual(interpolation_search(self.collection5, self.item5), None)
+        
+        self.assertEqual(interpolation_search(self.collection6, self.item6), self.collection6.index(self.item6))
+        
+        self.assertEqual(interpolation_search(self.collection7, self.item7), None)
+        
+
+
+class Test_interpolation_search_by_recursion(unittest.TestCase):
+    def setUp(self):
+        # un-sorted case
+        self.collection1 = [5,3,4,6,7]
+        self.item1 = 4
+        # sorted case, result exists
+        self.collection2 = [10,30,40,45,50,66,77,93]
+        self.item2 = 66
+        # sorted case, result doesn't exist
+        self.collection3 = [10,30,40,45,50,66,77,93]
+        self.item3 = 67
+        # equal elements case, result exists
+        self.collection4 = [10,10,10,10,10]
+        self.item4 = 10
+        # equal elements case, result doesn't exist
+        self.collection5 = [10,10,10,10,10]
+        self.item5 = 3
+        # 1 element case, result exists
+        self.collection6 = [10]
+        self.item6 = 10
+        # 1 element case, result doesn't exists
+        self.collection7 = [10]
+        self.item7 = 1
+
+    def tearDown(self):
+        pass
+
+    def test_interpolation_search_by_recursion(self):
+        self.assertEqual(interpolation_search_by_recursion(self.collection1, self.item1, 0, len(self.collection1)-1), None)
+        
+        self.assertEqual(interpolation_search_by_recursion(self.collection2, self.item2, 0, len(self.collection2)-1), self.collection2.index(self.item2))
+        
+        self.assertEqual(interpolation_search_by_recursion(self.collection3, self.item3, 0, len(self.collection3)-1), None)
+        
+        self.assertEqual(interpolation_search_by_recursion(self.collection4, self.item4, 0, len(self.collection4)-1), self.collection4.index(self.item4))
+
+        self.assertEqual(interpolation_search_by_recursion(self.collection5, self.item5, 0, len(self.collection5)-1), None)
+        
+        self.assertEqual(interpolation_search_by_recursion(self.collection6, self.item6, 0, len(self.collection6)-1), self.collection6.index(self.item6))
+        
+        self.assertEqual(interpolation_search_by_recursion(self.collection7, self.item7, 0, len(self.collection7)-1), None)
+ 
+
+
+if __name__ == '__main__':
+    unittest.main()