Create TimSort.py

Author: riteek27

TimSort.py

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+# Python3 program to perform basic timSort
+MIN_MERGE = 32
+
+
+def calcMinRun(n):
+	"""Returns the minimum length of a
+	run from 23 - 64 so that
+	the len(array)/minrun is less than or
+	equal to a power of 2.
+
+	e.g. 1=>1, ..., 63=>63, 64=>32, 65=>33,
+	..., 127=>64, 128=>32, ...
+	"""
+	r = 0
+	while n >= MIN_MERGE:
+		r |= n & 1
+		n >>= 1
+	return n + r
+
+
+# This function sorts array from left index to
+# to right index which is of size atmost RUN
+def insertionSort(arr, left, right):
+	for i in range(left + 1, right + 1):
+		j = i
+		while j > left and arr[j] < arr[j - 1]:
+			arr[j], arr[j - 1] = arr[j - 1], arr[j]
+			j -= 1
+
+
+# Merge function merges the sorted runs
+def merge(arr, l, m, r):
+
+	# original array is broken in two parts
+	# left and right array
+	len1, len2 = m - l + 1, r - m
+	left, right = [], []
+	for i in range(0, len1):
+		left.append(arr[l + i])
+	for i in range(0, len2):
+		right.append(arr[m + 1 + i])
+
+	i, j, k = 0, 0, l
+
+	# after comparing, we merge those two array
+	# in larger sub array
+	while i < len1 and j < len2:
+		if left[i] <= right[j]:
+			arr[k] = left[i]
+			i += 1
+
+		else:
+			arr[k] = right[j]
+			j += 1
+
+		k += 1
+
+	# Copy remaining elements of left, if any
+	while i < len1:
+		arr[k] = left[i]
+		k += 1
+		i += 1
+
+	# Copy remaining element of right, if any
+	while j < len2:
+		arr[k] = right[j]
+		k += 1
+		j += 1
+
+
+# Iterative Timsort function to sort the
+# array[0...n-1] (similar to merge sort)
+def timSort(arr):
+	n = len(arr)
+	minRun = calcMinRun(n)
+
+	# Sort individual subarrays of size RUN
+	for start in range(0, n, minRun):
+		end = min(start + minRun - 1, n - 1)
+		insertionSort(arr, start, end)
+
+	# Start merging from size RUN (or 32). It will merge
+	# to form size 64, then 128, 256 and so on ....
+	size = minRun
+	while size < n:
+
+		# Pick starting point of left sub array. We
+		# are going to merge arr[left..left+size-1]
+		# and arr[left+size, left+2*size-1]
+		# After every merge, we increase left by 2*size
+		for left in range(0, n, 2 * size):
+
+			# Find ending point of left sub array
+			# mid+1 is starting point of right sub array
+			mid = min(n - 1, left + size - 1)
+			right = min((left + 2 * size - 1), (n - 1))
+
+			# Merge sub array arr[left.....mid] &
+			# arr[mid+1....right]
+			if mid < right:
+				merge(arr, left, mid, right)
+
+		size = 2 * size
+
+
+# Driver program to test above function
+if __name__ == "__main__":
+
+	arr = [-2, 7, 15, -14, 0, 15, 0,
+		7, -7, -4, -13, 5, 8, -14, 12]
+
+	print("Given Array is")
+	print(arr)
+
+	# Function Call
+	timSort(arr)
+
+	print("After Sorting Array is")
+	print(arr)
+