Given two strings S1 and S2, representing sentences, the task is to print both sentences after removing all words which are present in both sentences.
Input: S1 = “sky is blue in color”, S2 =”Raj likes sky blue color “
Output: is in
Raj likes
Explanation: The common words are [ sky, blue, color ]. Removing these words from the two sentences modifies the sentences to the specified output.Input: S1 = “learn data structures and algorithms in neveropen“, S2 = “neveropen is the computer science portal for Geeks“
Output: learn data structures and algorithms in
is the computer science portal for.
Approach using Hashing: The problem can be solved using Counter() function. Follow the steps below to solve the problem:
- As all the words in a sentence are separated by spaces, split the words by spaces using split() and store them in a List.
- Initialize two lists, say sentence1 and sentence2, to store the words of the two given sentences.
- Count frequencies of the words of both sentences using the Counter() function and store it in dictionaries frequency1 and frequency2.
- Traverse the list sentence1 and remove the words which are present in the dictionary frequency2.
- Traverse the list sentence2 and remove the words which are present in the dictionary frequency1.
- Print both the lists.
Below is the implementation of the above approach:
Python3
# Python program for the above approachfrom collections import Counter# Function to remove common# words from two stringsdef removeCommonWords(sent1, sent2): # Store the words present # in both the sentences sentence1 = list(sent1.split()) sentence2 = list(sent2.split()) # Calculate frequency of words # using Counter() function frequency1 = Counter(sentence1) frequency2 = Counter(sentence2) word = 0 # Iterate the list consisting # of words in the first sentence for i in range(len(sentence1)): # If word is present # in both the strings if sentence1[word] in frequency2.keys(): # Remove the word sentence1.pop(word) # Decrease the frequency of the word word = word-1 word += 1 word = 0 # Iterate the list consisting of # words in the second sentence for i in range(len(sentence2)): # If word is present # in both the strings if sentence2[word] in frequency1.keys(): # Remove the word sentence2.pop(word) # Decrease the removed word word = word-1 word += 1 # Print the remaining # words in the two sentences print(*sentence1) print(*sentence2)# Driver Codesentence1 = "sky is blue in color"sentence2 = "raj likes sky blue color"removeCommonWords(sentence1, sentence2) |
is in raj likes
Time Complexity: O((max(N, M))2)
Auxiliary Space: O(max(N, M))
Approach using Sets and Lists: Follow the steps below to solve the problem:
- As all the words in a sentence are separated by spaces, split the words by spaces using split() and store them in a List.
- Initialize two lists, say sentence1 and sentence2, to store the words of the two given sentences.
- Convert the two Lists into Sets, say sen1 and sen2.
- Now, find the set intersection of two sets, to store words that are common in both the sentences, say common.
- Traverse the List sentence1 and pop all the words which are present in the set intersection of two sentences.
- Repeat the same for the second sentence.
- Finally, print the remaining words in the two Lists.
Below is the implementation of the above approach:
Python3
# Python program to implement# the above approach# Function to return the words which# are common in both the sentencesdef commonWords(sent1, sent2): # Splitting the words in a set sen1 = set(sent1) sen2 = set(sent2) # Stores the list of common words common = list(sen1.intersection(sen2)) # Return the list return common# Function to remove all the words# that are common in both the stringsdef removeCommonWords(sent1, sent2): # Stores the words of the # sentences in separate lists sentence1 = list(sent1.split()) sentence2 = list(sent2.split()) # Find the words that are # common in both the sentences commonlist = commonWords(sentence1, sentence2) word = 0 # Iterate the list of words # of the first sentence for i in range(len(sentence1)): # If word is common in both lists if sentence1[word] in commonlist: # Remove the word sentence1.pop(word) # Decrease the removed word word = word - 1 word += 1 word = 0 # Iterate the list of words # of the second sentence for i in range(len(sentence2)): # If word is common in both lists if sentence2[word] in commonlist: # Remove the word sentence2.pop(word) # Decrease the removed word word = word-1 word += 1 # Print the remaining words # in both the sentences print(*sentence1) print(*sentence2)# Driver CodeS1 = "sky is blue in color"S2 = "Raj likes sky blue color"removeCommonWords(S1, S2) |
is in Raj likes
Time Complexity: O(max(N, M))
Auxiliary Space: O(max(N, M))
Approach Using Lists and remove():
In this approach we are using remove method in the lists to remove the common words two strings.
in this we use slip() method to covert strings into list, and we use in operator to check the common elements.
By using the remove() method we will remove the common words in the two sentences.
Python3
def removeCommonWords(sent1,sent2): com=[] sent1=list(sentence1.split()) sent2=list(sentence2.split()) for i in sent1: if i in sent2: sent1.remove(i) sent2.remove(i) print(*sent1) print(*sent2)sentence1 = "sky is blue in color"sentence2 = "raj likes sky blue color"removeCommonWords(sentence1,sentence2) |
is in raj likes
Time Complexity: O(n2)
Auxiliary Space: O(n)
Approach Using Operator.countOf() function:
Python3
import operator as opdef removeCommonWords(sent1,sent2): com=[] sent1=list(sentence1.split()) sent2=list(sentence2.split()) for i in sent1: if op.countOf(sent2,i)>0: sent1.remove(i) sent2.remove(i) print(*sent1) print(*sent2)sentence1 = "sky is blue in color"sentence2 = "raj likes sky blue color"removeCommonWords(sentence1,sentence2) |
is in raj likes
Time Complexity: O(n2)
Auxiliary Space: O(n)
Approach: itertools and reduce methods:
Algorithm :
- Split the two input sentences into lists of words.
- Compute the set intersection of the two lists to find common words.
- Filter out the common words from both sentences.
- Print the remaining words in each sentence.
Python3
import itertoolsfrom functools import reducedef removeCommonWords(sent1, sent2): sent1 = list(sentence1.split()) sent2 = list(sentence2.split()) common_words = set(sent1).intersection(sent2) sent1 = list(filter(lambda x: x not in common_words, sent1)) sent2 = list(filter(lambda x: x not in common_words, sent2)) print(*sent1) print(*sent2)sentence1 = "sky is blue in color"sentence2 = "raj likes sky blue color"removeCommonWords(sentence1, sentence2)#This code is contributed by Jyothi pinjala. |
is in raj likes
The time complexity: O(n^2) because of the nested loop of the set intersection operation, where n is the length of the longest sentence. The filter function has a linear time complexity of O(n) in the worst case, where n is the length of the input list.
The space complexity: O(n) because we are creating two separate lists for each sentence, and potentially creating a set that could be as large as the length of the longest sentence.
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