Ratsun reitit

n = gets.to_i
q = Queue.new
q << [0, 0]
dist = Array.new(n) { Array.new(n, -1) }
dist[0][0] = 0
while q.size.positive?
  i, j = q.pop
  (-2..2).each do |ci|
    (-2..2).each do |cj|
      next if ci.abs + cj.abs != 3
      ni = i + ci
      nj = j + cj
      next if [ni, nj].min.negative? || ([ni, nj].max >= n)
      next if dist[ni][nj] != -1

      dist[ni][nj] = dist[i][j] + 1
      q << [ni, nj]
    end
  end
end
dist.each do |x|
  puts x * ' '
end

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3

Verdict: ACCEPTED

Test 3

Group: 1, 2, 3

Verdict: ACCEPTED

Test 4

Group: 1, 2, 3

Verdict: ACCEPTED

Test 5

Group: 1, 2, 3

Verdict: ACCEPTED

Test 6

Group: 1, 2, 3

Verdict: ACCEPTED

Test 7

Group: 1, 2, 3

Verdict: ACCEPTED

Test 8

Group: 2, 3

Verdict: ACCEPTED

Test 9

Group: 2, 3

Verdict: ACCEPTED

Test 10

Group: 2, 3

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED