public class Solution {    public int FindPoisonedDuration(int[] timeSeries, int duration) {        if (timeSeries == null || timeSeries.Length == 0)            {                return 0;            }            else if (timeSeries.Length == 1)            {                return duration;            }            else            {                var sum = 0;                for (int i = 0; i < timeSeries.Length - 1; i++)                {                    var cur = timeSeries[i];                    var next = timeSeries[i + 1];                    if (cur + duration <= next)                    {                        sum += duration;                    }                    else                    {                        sum += next - cur;                    }                }                sum += duration;                return sum;            }    }}