5.7.rb

def getNext (x,y,map)
  col=map.first.length
  row=map.length
  max=map[x][y]
  next_cell=[x,y]
  
  if 0<x and map[x-1][y]> max 
    max=map[x-1][y]
    next_cell=[x-1,y]
  end

  if 0<y and map[x][y-1]> max 
    max=map[x][y-1]
    next_cell=[x,y-1]
  end

  if x<row-1 and map[x+1][y]> max 
    max=map[x+1][y]
    next_cell=[x+1,y]
  end

  if y<col-1 and map[x][y+1]> max 
    max=map[x][y+1]
    next_cell=[x,y+1]
  end
  return nil if next_cell[0]==x && next_cell[1]==y 
  next_cell

end

def dfs (x,y,map)
  local_peak=[x,y]
  
  while true
    res= getNext(local_peak[0],local_peak[1],map)
    local_peak=res unless res.nil?
    return local_peak if res.nil?
  end
end

def greatest_peaks(map)
  # write your code here
  peaks=Hash.new 0
  map.length.times do |i|
    map.first.length.times do |j|
      peaks[dfs(i,j,map)]+=1
    end
  end
  min=nil
  max=nil
  peaks.each do |key,value|
    min = value if min.nil? or value<min
    max = value if max.nil? or value>max
  end
  [min,max]
end

greatest_peaks(
  [
    [9, 8, 5], 
    [5, 6, 3], 
    [8, 4, 1]
  ]
)
# => [3, 6]
=begin
p greatest_peaks(
  [
    [8, 12], 
    [9, 3]
  ]
)
# => [1, 3]
=end