leetcode983

public class Solution
    {
        public int MincostTickets(int[] days, int[] costs)
        {
            int weeklyStart = ;
            int monthlyStart = ;
            int[] dp = new int[days.Length + ];
            dp[] = ;

            for (int i = ; i <= days.Length; i++)
            {
                // day pass
                dp[i] = dp[i - ] + costs[];

                // update best weekly pass start date
                while (days[i - ] - days[weeklyStart] >= ) weeklyStart++;

                // update best monthly pass start date
                while (days[i - ] - days[monthlyStart] >= ) monthlyStart++;

                // get minimum of all 3 above
                dp[i] = Math.Min(dp[i], Math.Min(dp[weeklyStart] + costs[], dp[monthlyStart] + costs[]));
            }

            return dp[days.Length];
        }
    }