Ruby で作った

scores = [1,2,9,2,3,9,7]

results = scores.each_with_object([]).with_index do |(score, ary), i|
if ary.empty? || ary[0][0] == score
ary << [score, i]
elsif ary[0][0] < score
ary.clear
ary << [score, i]
end
end

results.each do |item|
puts "score: #{item[0]}, index: #{item[1]}"
end

出力
score: 9, index: 2
score: 9, index: 5