Create hacktoberfest

String/subsequencer.py

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+
+import math
+
+sn = []
+global m
+m = 0
+
+# Function for generating
+# the subsequences
+
+
+def subsequences(s, op, i, j):
+
+	# Base Case
+	if(i == m):
+		op[j] = None
+		temp = "".join([i for i in op if i])
+
+		# Insert each generated
+		# subsequence into the set
+		sn.append(temp)
+		return
+
+	# Recursive Case
+	else:
+
+		# When a particular
+		# character is taken
+		op[j] = s[i]
+
+		subsequences(s, op,
+					i + 1, j + 1)
+
+		# When a particular
+		# character isn't taken
+		subsequences(s, op,
+					i + 1, j)
+		return
+
+
+# Driver Code
+str = "dd"
+m = len(str)
+n = int(math.pow(2, m) + 1)
+
+# Output array for storing
+# the generating subsequences
+# in each call
+op = [None for i in range(n)]
+
+# Function Call
+subsequences(str, op, 0, 0)
+
+# Output will be the number
+# of elements in the set
+print(len(set(sn)))
+