Submission #2789430

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Source Code Expand

N, K = gets.split.map(&:to_i)
K2 = 2 * K
m = Array.new(K2 + 1){Array.new(K2 + 1, 0)}
readlines.map(&:split).each do |x, y, c|
  x = x.to_i % K2
  y = (y.to_i + (c == 'W' ? K : 0)) % K2
  m[x + 1][y + 1] += 1
  m[(x + K) % K2 + 1][(y + K) % K2 + 1] += 1
end
(1 .. K2).each do |i|
  (1 .. K2).each do |j|
    m[i][j] += m[i - 1][j] + m[i][j - 1] - m[i - 1][j - 1]
  end
end
ans = 0
(1 .. K).each do |i|
  (1 .. K).each do |j|
    c = m[i + K][j + K] - m[i][j + K] - m[i + K][j] + m[i][j]
    ans = c if c > ans
    c = N - c
    ans = c if c > ans
  end
end
puts ans

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