Python Counter | Majority Element
Majority Element: A majority element in an array A[] of size n is an element that appears more than n/2 times (and hence there is at most one such element).
Write a function which takes an array and emits the majority element (if it exists), otherwise prints NONE as follows:
Examples:
Input : 3 3 4 2 4 4 2 4 4 Output : 4 Input : 3 3 4 2 4 4 2 4 Output : NONE
We have existing solution for this problem please refer Majority Element link. We can solve this problem quickly in Python using Counter(iterable) function. Approach is simple,
- Convert given list of elements into dictionary using Counter() method, having elements as keys and their frequencies as value.
- Now traverse complete dictionary and check for element whose frequency follows the condition greater than (n/2) where n is size of list. That element will be majority element.
# Function to find majority element from collections import Counter def majority(arr): # convert array into dictionary freqDict = Counter(arr) # traverse dictionary and check majority element size = len(arr) for (key,val) in freqDict.items(): if (val > (size/2)): print(key) return print('None') # Driver program if __name__ == "__main__": arr = [3,3,4,2,4,4,2,4,4] majority(arr) |
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Output:
4
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