Iterative Merge Sort

implementation of Iterative Merge Sort.

Author: mohd-mehraj

Sorting Algorithims/Iterative Merge Sort

@@ -0,0 +1,83 @@
+# Iterative Merge sort (Bottom Up) 
+
+# Iterative mergesort function to 
+# sort arr[0...n-1] 
+def mergeSort(a): 
+	
+	current_size = 1
+	
+	# Outer loop for traversing Each 
+	# sub array of current_size 
+	while current_size < len(a) - 1: 
+		
+		left = 0
+		# Inner loop for merge call 
+		# in a sub array 
+		# Each complete Iteration sorts 
+		# the iterating sub array 
+		while left < len(a)-1: 
+			
+			# mid index = left index of 
+			# sub array + current sub 
+			# array size - 1 
+			mid = min((left + current_size - 1),(len(a)-1)) 
+			
+			# (False result,True result) 
+			# [Condition] Can use current_size 
+			# if 2 * current_size < len(a)-1 
+			# else len(a)-1 
+			right = ((2 * current_size + left - 1, 
+					len(a) - 1)[2 * current_size 
+						+ left - 1 > len(a)-1]) 
+							
+			# Merge call for each sub array 
+			merge(a, left, mid, right) 
+			left = left + current_size*2
+			
+		# Increasing sub array size by 
+		# multiple of 2 
+		current_size = 2 * current_size 
+
+# Merge Function 
+def merge(a, l, m, r): 
+	n1 = m - l + 1
+	n2 = r - m 
+	L = [0] * n1 
+	R = [0] * n2 
+	for i in range(0, n1): 
+		L[i] = a[l + i] 
+	for i in range(0, n2): 
+		R[i] = a[m + i + 1] 
+
+	i, j, k = 0, 0, l 
+	while i < n1 and j < n2: 
+		if L[i] > R[j]: 
+			a[k] = R[j] 
+			j += 1
+		else: 
+			a[k] = L[i] 
+			i += 1
+		k += 1
+
+	while i < n1: 
+		a[k] = L[i] 
+		i += 1
+		k += 1
+
+	while j < n2: 
+		a[k] = R[j] 
+		j += 1
+		k += 1
+
+
+# Driver code 
+a = [12, 11, 13, 5, 6, 7] 
+print("Given array is ") 
+print(a) 
+
+mergeSort(a) 
+
+print("Sorted array is ") 
+print(a) 
+
+#  This code is contributed by mohd-mehraj.