Merge pull request #36 from prasannassp/main

Merge Sort added

Sorting/Merge_Sort.py

@@ -0,0 +1,61 @@
+#Merge Sort - a way of sorting, which uses divide and conquer method.
+
+def merge_sort(values): 
+
+	# Splitting of list into approximately two equal halves
+	if len(values)>1: 
+		m = len(values)//2  
+
+		# Splitting left and right sublists
+		left = values[:m] 
+		right = values[m:] 
+
+		# Recrusive call to merge_sort to do the same process for the available sublist
+		left = merge_sort(left) 
+		right = merge_sort(right) 
+
+		values =[] 
+
+		# Comparing the first elements of both sublists and appending the lowest of two to "values" list
+		# list.pop(0) => removes the first element (0th index) of list
+		while len(left)>0 and len(right)>0: 
+
+			# condition that, left sublist element is lesser than that of right
+			if left[0]<right[0]: 
+				values.append(left[0]) 
+				left.pop(0)
+
+			# condition that, right sublist element is greater than or equal to that of left
+			else: 
+				values.append(right[0]) 
+				right.pop(0) 
+
+		# Assuming that either of the list becomes null, where other still has elements in it
+		# Left sublist has elements, Right sublist is null
+		for i in left: 
+			values.append(i) 
+
+		# Right sublist has elements, Left sublist is null
+		for i in right: 
+			values.append(i) 
+
+	# After appending the sorted order, the list is returned to the position, where it was called recently
+	return values 
+
+
+# Input - list
+a = list(map(int, input("Enter space-splitted values: ").split(' ')))
+print("Given array is") 
+print(a) 
+
+# Calling the function which performs merge sort
+a = merge_sort(a) 
+
+# Output
+print("Sorted array is : ") 
+print(a) 
+
+'''Expected Input/Output:
+ Input: [5, 3, 12, 8, 7, 9]
+Output: [3, 5, 7, 8, 9, 12]
+'''