Given a string S, remove all the consecutive duplicates. Examples:
Input : aaaaabbbbbb Output : ab Input : neveropen Output : geksforgeks Input : aabccba Output : abcba
We have existing solution for this problem please refer Remove all consecutive duplicates from the string link. We can solve this problem in python quickly using itertools.groupby() method.
How itertools.groupby(iterable,key[optional]) works in Python?
Group by method takes two input one is iterable (list,tuple,dictionary) and second is key function which calculates keys for each element present in iterable. It returns key and iterable of grouped items. If key function not specified or is None, key defaults to an identity function and returns the element unchanged. For example,
Python3
numbers = [1, 1, 1, 3, 3, 2, 2, 2, 1, 1]import itertoolsfor (key,group) in itertools.groupby(numbers): print (key,list(group)) |
Output
1 [1, 1, 1] 3 [3, 3] 2 [2, 2, 2] 1 [1, 1]
Python3
# function to remove all consecutive duplicates # from the string in Python from itertools import groupby def removeAllConsecutive(input): # group all consecutive characters based on their # order in string and we are only concerned # about first character of each consecutive substring # in given string, so key value will work for us # and we will join these keys without space to # generate resultant string result = [] for (key,group) in groupby(input): result.append(key) print (''.join(result)) # Driver program if __name__ == "__main__": input = 'aaaaabbbbbb' removeAllConsecutive(input) |
Output
ab
Time complexity : O(n)
Auxiliary Space : O(n)
