Added Majority Voting Algorithm

[sarvjeetdev]

Describe your change:

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

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[cclauss]

If partition is min_votes_required then how does this algorithm use a constant number of words of memory as discussed in the Wikipedia article? If there are 30 candidates then there will ~10 times as much memory used than 3 candidates.

[sarvjeetdev]

Problem : We need to find the elements (votes or candidates) that appear at least floor( total votes / k) times ,( here k is partitioning the array i.e. total_votes, that's why I named it partition before ). We need to solve in a linear time. This is not representing real world voting.

This was a problem came in an interview that I attended. Assuming that we have all the votes and the factor is fixed like 2 or 3. What I have contributed is a general case of the algorithm.

[sarvjeetdev]

I know this is not very special algo but It was something new in the interview and I wanted to contribute for the Hacktoberfest and that's the reason I submitted this.

[cclauss]

OK... Following the pseudocode and the graph in the wiki article...

We need two functions.
The first one takes in only votes and it only has three local variables (fixed memory size): candidate (fka m), i, and vote (fka x) and returns only one value: candidate. The phase 1 function should not use a Counter.

The candidates are:
B Blue circle
R Red square
Y Yellow star

>>> votes = "BBRBRYYRRRBRRYRR"
>>> def majority_vote_pass_one(votes):
...     candidate = None
...     i = 0
...     for vote in votes:
...         if i == 0:
...             candidate = vote
...             i = 1
...         elif candidate == vote:
...             i += 1
...         else:
...             i -= 1
...         print(f"{vote = }, {candidate = }, {i = }")
...     return candidate
...
>>> majority_vote_pass_one(votes)
vote = 'B', candidate = 'B', i = 1
vote = 'B', candidate = 'B', i = 2
vote = 'R', candidate = 'B', i = 1
vote = 'B', candidate = 'B', i = 2
vote = 'R', candidate = 'B', i = 1
vote = 'Y', candidate = 'B', i = 0
vote = 'Y', candidate = 'Y', i = 1
vote = 'R', candidate = 'Y', i = 0
vote = 'R', candidate = 'R', i = 1
vote = 'R', candidate = 'R', i = 2
vote = 'B', candidate = 'R', i = 1
vote = 'R', candidate = 'R', i = 2
vote = 'R', candidate = 'R', i = 3
vote = 'Y', candidate = 'R', i = 2
vote = 'R', candidate = 'R', i = 3
vote = 'R', candidate = 'R', i = 4
'R'

[cclauss]

Nice! Thanks for your patience!

[sarvjeetdev]

Thank you so much, this was my first time, finally did it. Thanks a lot for the support and sorry for the mistakes. Keep up the good work. God bless you.