We are given a string and we need to remove all duplicates from it? What will be the output if the order of character matters? Examples:
Input : geeksforgeeks
Output : geksfor
This problem has an existing solution please refer to Remove all duplicates from a given string.
Method 1:
from collections import OrderedDict
# Function to remove all duplicates from string # and order does not matter def removeDupWithoutOrder( str ):
# set() --> A Set is an unordered collection
# data type that is iterable, mutable,
# and has no duplicate elements.
# "".join() --> It joins two adjacent elements in
# iterable with any symbol defined in
# "" ( double quotes ) and returns a
# single string
return "".join( set ( str ))
# Function to remove all duplicates from string # and keep the order of characters same def removeDupWithOrder( str ):
return "".join(OrderedDict.fromkeys( str ))
# Driver program if __name__ = = "__main__" :
str = "geeksforgeeks"
print ( "Without Order = " ,removeDupWithoutOrder( str ))
print ( "With Order = " ,removeDupWithOrder( str ))
|
Without Order = foskerg With Order = geksfor
Time complexity: O(n)
Auxiliary Space: O(n)
Method 2:
def removeDuplicate( str ):
s = set ( str )
s = "".join(s)
print ( "Without Order:" ,s)
t = ""
for i in str :
if (i in t):
pass
else :
t = t + i
print ( "With Order:" ,t)
str = "geeksforgeeks"
removeDuplicate( str )
|
Without Order: kogerfs With Order: g With Order: ge With Order: ge With Order: gek With Order: geks With Order: geksf With Order: geksfo With Order: geksfor With Order: geksfor With Order: geksfor With Order: geksfor With Order: geksfor With Order: geksfor
Time complexity: O(n)
Auxiliary Space: O(n)
What do OrderedDict and fromkeys() do?
An OrderedDict is a dictionary that remembers the order of the keys that were inserted first. If a new entry overwrites an existing entry, the original insertion position is left unchanged.
For example, see below code snippet :
from collections import OrderedDict
ordinary_dictionary = {}
ordinary_dictionary[ 'a' ] = 1
ordinary_dictionary[ 'b' ] = 2
ordinary_dictionary[ 'c' ] = 3
ordinary_dictionary[ 'd' ] = 4
ordinary_dictionary[ 'e' ] = 5
# Output = {'a': 1, 'c': 3, 'b': 2, 'e': 5, 'd': 4} print (ordinary_dictionary)
ordered_dictionary = OrderedDict()
ordered_dictionary[ 'a' ] = 1
ordered_dictionary[ 'b' ] = 2
ordered_dictionary[ 'c' ] = 3
ordered_dictionary[ 'd' ] = 4
ordered_dictionary[ 'e' ] = 5
# Output = {'a':1,'b':2,'c':3,'d':4,'e':5} print (ordered_dictionary)
|
{'a': 1, 'b': 2, 'c': 3, 'd': 4, 'e': 5} OrderedDict([('a', 1), ('b', 2), ('c', 3), ('d', 4), ('e', 5)])
Time complexity: O(n)
Auxiliary Space: O(1)
fromkeys() creates a new dictionary with keys from seq and values set to a value and returns a list of keys, fromkeys(seq[, value]) is the syntax for fromkeys() method. Parameters :
- seq : This is the list of values that would be used for dictionary keys preparation.
- value : This is optional, if provided then the value would be set to this value.
For example, see below code snippet :
from collections import OrderedDict
seq = ( 'name' , 'age' , 'gender' )
dict = OrderedDict.fromkeys(seq)
# Output = {'age': None, 'name': None, 'gender': None} print ( str ( dict ))
dict = OrderedDict.fromkeys(seq, 10 )
# Output = {'age': 10, 'name': 10, 'gender': 10} print ( str ( dict ))
|
OrderedDict([('name', None), ('age', None), ('gender', None)]) OrderedDict([('name', 10), ('age', 10), ('gender', 10)])
Time complexity: O(n)
Auxiliary Space: O(1)
Method 5: using operator.countOf() method
import operator as op
def removeDuplicate( str ):
s = set ( str )
s = "".join(s)
print ( "Without Order:" , s)
t = ""
for i in str :
if op.countOf(t, i) > 0 :
pass
else :
t = t + i
print ( "With Order:" , t)
str = "geeksforgeeks"
removeDuplicate( str )
|
Without Order: goksefr With Order: g With Order: ge With Order: ge With Order: gek With Order: geks With Order: geksf With Order: geksfo With Order: geksfor With Order: geksfor With Order: geksfor With Order: geksfor With Order: geksfor With Order: geksfor
Time Complexity: O(N)
Auxiliary Space : O(N)