We are given list of n number of arrays, find all common elements in given arrays ? Examples:
Input : arr = [[1,2,3,4],
[8,7,3,2],
[9,2,6,3],
[5,1,2,3]]
Output : Common Elements = [2,3]
We can solve this problem quickly in python using intersection_update() method of Set() data structure. How intersection_update() works ?
Suppose we have two sets A and B, then A.intersection_update(B) operation updates set A with common elements in set A and B. For example, A=set([1,2,3]) and B=set([4,2,3]) now after taking A.intersection_update(B), value of set A will be [2,3]. Syntax is anySet.intersection_update(iterable).
Implementation:
Python3
# Function to find common elements in n arraysdef commonElements(arr): # initialize result with first array as a set result = set(arr[0]) # now iterate through list of arrays starting from # second array and take intersection_update() of # each array with result. Every operation will # update value of result with common values in # result set and intersected set for currSet in arr[1:]: result.intersection_update(currSet) return list(result)# Driver codeif __name__ == "__main__": arr = [[1,2,3,4], [8,7,3,2], [9,2,6,3], [5,1,2,3]] output = commonElements(arr) if len(output) > 0: print ("Common Element = ",output) else: print ('No Common Elements Found') |
Common Element = [2, 3]
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