Daily Temperatures

  # 4. Daily Temperatures
  # Problem: For each day, return the number of days to wait for a warmer temperature.
  # Input: [73,74,75,71,69,72,76,73], Output: [1,1,4,2,1,1,0,0]
  # Time Complexity: O(n)
  def daily_temperatures(temps)
    result = Array.new(temps.size, 0)
    stack = []
    temps.each_with_index do |temp, today|
      while !stack.empty? && temps[stack.last] < temp
        prev_day = stack.pop
        result[prev_day] = today - prev_day
        puts "Found warmer day: #{prev_day} -> #{today} = #{result[prev_day]}"
      end
      stack.push(today)
    end
    result