Winning Candidate — LeetCode 574 Python Solution

The problem

Report the name of the candidate who received the most votes; the data guarantees exactly one winner. Candidate has id (int, unique) and name (varchar); Vote has id (int, primary key, autoincrementing) and candidateId (int), which references a candidate, with one row per vote cast. Return the winner in a column called name.

Example

Input

Candidate(id, name) = (1, 'Ana'), (2, 'Ben'), (3, 'Cleo'); Vote(id, candidateId) = (1, 2), (2, 2), (3, 3), (4, 2), (5, 1)

Output

name = 'Ben'

Explanation

Candidate 2 receives 3 votes to 1 each for candidates 1 and 3.

Python solution

import pandas as pd

def winning_candidate(candidate: pd.DataFrame, vote: pd.DataFrame) -> pd.DataFrame:
    counts = vote.groupby('candidateId').size()
    max_cnt = counts.max()
    winner_id = counts[counts == max_cnt].index.min()
    name = candidate.loc[candidate['id'] == winner_id, 'name'].iloc[0]
    return pd.DataFrame({'name': [name]})

Complexity

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