Create BitonicSort.py (#386)

sorts/BitonicSort.py

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+# Python program for Bitonic Sort. Note that this program 
+# works only when size of input is a power of 2. 
+
+# The parameter dir indicates the sorting direction, ASCENDING 
+# or DESCENDING; if (a[i] > a[j]) agrees with the direction, 
+# then a[i] and a[j] are interchanged.*/ 
+def compAndSwap(a, i, j, dire):
+    if (dire == 1 and a[i] > a[j]) or (dire == 0 and a[i] < a[j]):
+        a[i], a[j] = a[j], a[i]
+
+        # It recursively sorts a bitonic sequence in ascending order,
+
+
+# if dir = 1, and in descending order otherwise (means dir=0).
+# The sequence to be sorted starts at index position low, 
+# the parameter cnt is the number of elements to be sorted. 
+def bitonicMerge(a, low, cnt, dire):
+    if cnt > 1:
+        k = int(cnt / 2)
+        for i in range(low, low + k):
+            compAndSwap(a, i, i + k, dire)
+        bitonicMerge(a, low, k, dire)
+        bitonicMerge(a, low + k, k, dire)
+
+        # This funcion first produces a bitonic sequence by recursively
+
+
+# sorting its two halves in opposite sorting orders, and then
+# calls bitonicMerge to make them in the same order 
+def bitonicSort(a, low, cnt, dire):
+    if cnt > 1:
+        k = int(cnt / 2)
+        bitonicSort(a, low, k, 1)
+        bitonicSort(a, low + k, k, 0)
+        bitonicMerge(a, low, cnt, dire)
+
+        # Caller of bitonicSort for sorting the entire array of length N
+
+
+# in ASCENDING order
+def sort(a, N, up):
+    bitonicSort(a, 0, N, up)
+
+
+# Driver code to test above
+a = []
+
+n = int(input())
+for i in range(n):
+    a.append(int(input()))
+up = 1
+
+sort(a, n, up)
+print("\n\nSorted array is")
+for i in range(n):
+    print("%d" % a[i])