Add Tim Sort implementation

hemanth-kotagiri · hemanth-kotagiri · commit e08137879036 · 2020-11-02T22:24:17.000+05:30
diff --git a/algorithms/sorting/tim_sort.py b/algorithms/sorting/tim_sort.py
@@ -0,0 +1,90 @@
+from random import randint
+
+
+class TimSort:
+    """ A class to demonstrate Tim Sort """
+
+    def __init__(self, array):
+        self.array = array
+        self.arrayLength = len(array)
+        self.__RUN = 32
+
+    def insertionSort(self, arr):
+        """ Sorts the given array from given starting index to ending index """
+
+        for i in range(1, len(arr)):
+            currentElement = arr[i]
+            j = i - 1
+            while j >= 0 and arr[j] > currentElement:
+                arr[j + 1] = arr[j]
+                j -= 1
+            arr[j + 1] = currentElement
+
+        return arr
+
+    def mergeRuns(self, arr1, arr2):
+        """ Merges the given two arrays: arr1 and arr2 """
+
+        newArray = list()
+        lengthOfArr1 = len(arr1)
+        lengthOfArr2 = len(arr2)
+
+        # The variable i is used to keep track of the indices of the first array
+        # The variable j is used to keep track of the indices of the second array
+        # The variable k is used to keep track of the indices of the newArray array which is to be returned
+        i, j, k = 0, 0, 0
+
+        while i < lengthOfArr1 and j < lengthOfArr2:
+            if arr1[i] <= arr2[j]:
+                newArray[k] = arr1[i]
+                k += 1
+                i += 1
+            elif arr1[i] >= arr2[j]:
+                newArray[k] = arr2[j]
+                k += 1
+                j += 1
+
+            # The below two loops will append any remaining elements left in any of the two arrays.
+            while i < lengthOfArr1:
+                newArray.append(arr1[i])
+                i += 1
+
+            while j < lengthOfArr2:
+                newArray.append(arr2[j])
+                j += 1
+
+        return newArray
+
+    def changeRun(self, newRun):
+        self.__RUN = newRun
+
+    def algorithm(self):
+        """ This function will perfom Tim Sort on the given array """
+
+        # Breaking the array into chunks of subarray(RUNS) of size RUN and perfomring insertionSort on them.
+        for i in range(0, self.arrayLength, self.__RUN):
+            currentRunElements = self.array[i: i + self.__RUN]
+
+            self.array[i: i +
+                       self.__RUN] = self.insertionSort(currentRunElements)
+
+        temp_runner = self.__RUN
+        while temp_runner < self.arrayLength:
+            for idx in range(0, self.arrayLength, temp_runner * 2):
+                firstArray = self.array[idx: idx + temp_runner]
+                secondArray = self.array[idx +
+                                         temp_runner: idx + temp_runner * 2]
+                self.array[idx: idx + temp_runner *
+                           2] = self.mergeRuns(firstArray, secondArray)
+            temp_runner = self.__RUN * 2
+
+        print(f"The sorted array is : {self.array}")
+
+    def __repr__(self):
+        return f"Array: {self.array}\nRUN: {self.__RUN}"
+
+
+myArray = [randint(1, 100) for i in range(15)]
+demo = TimSort(myArray)
+print(demo)
+demo.algorithm()
