Rosetta Code

Top rank per group

Pick the highest-scoring row from each group with a stable tie-break on name.

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Sourcerosettacode/popular/top_rank_per_group.vibe
def rows -> array<{ group: string, name: string, score: int }>
  [
    { group: "blue", name: "Ava", score: 92 },
    { group: "blue", name: "Ben", score: 88 },
    { group: "green", name: "Noah", score: 77 },
    { group: "green", name: "Mia", score: 91 },
    { group: "red", name: "Zoe", score: 84 },
    { group: "red", name: "Eli", score: 84 }
  ]
end

def better_rank?(
  candidate: { group: string, name: string, score: int },
  current: nil | { group: string, name: string, score: int }
) -> bool
  if current == nil
    true
  elsif candidate["score"] > current["score"]
    true
  elsif candidate["score"] < current["score"]
    false
  else
    candidate["name"] < current["name"]
  end
end

def top_rank_per_group(
  rows: array<{ group: string, name: string, score: int }>
) -> array<{ group: string, name: string, score: int }>
  best: hash<string, { group: string, name: string, score: int }> = {}
  index = 0

  while index < rows.length
    row = rows.fetch(index)
    key = row["group"]
    if better_rank?(row, best[key])
      best[key] = row
    end
    index = index + 1
  end

  groups = ["blue", "green", "red"]
  output: array<{ group: string, name: string, score: int }> = []
  index = 0
  while index < groups.length
    output.push(best.fetch(groups.fetch(index)))
    index = index + 1
  end

  output
end

def run -> array<{ group: string, name: string, score: int }>
  top_rank_per_group(rows)
end

Output

Click Run example to see the result.

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