AnotherReplayReader/Utils/TimeIndexedPrefixSums.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace AnotherReplayReader.Utils
{
    public record TimeIndexedPrefixSums(List<TimeSpan> Times, List<int> PrefixSums)
    {
        public void Add(TimeSpan time, int value)
        {
            if (Times.Count > 0 && time < Times.Last())
            {
                throw new ArgumentException("Time must be added in non-decreasing order.");
            }
            Times.Add(time);
            PrefixSums.Add((PrefixSums.LastOrDefault()) + value);
        }

        public int Query(TimeSpan start, TimeSpan end)
        {
            var times = Times;
            var prefix = PrefixSums;

            int startIndex = LowerBound(times, start);
            int endIndex = UpperBound(times, end);

            if (startIndex >= times.Count || endIndex < 0 || startIndex > endIndex)
            {
                return 0;
            }

            int result = prefix[endIndex];

            if (startIndex > 0)
            {
                result -= prefix[startIndex - 1];
            }

            return result;
        }

        public int GetTotal()
        {
            return PrefixSums.LastOrDefault();
        }

        public static int LowerBound(List<TimeSpan> arr, TimeSpan target)
        {
            int left = 0, right = arr.Count;

            while (left < right)
            {
                int mid = left + (right - left) / 2;

                if (arr[mid] < target)
                {
                    left = mid + 1;
                }
                else
                {
                    right = mid;
                }
            }

            return left;
        }

        public static int UpperBound(List<TimeSpan> arr, TimeSpan target)
        {
            int left = 0, right = arr.Count;

            while (left < right)
            {
                int mid = left + (right - left) / 2;

                if (arr[mid] <= target)
                {
                    left = mid + 1;
                }
                else
                {
                    right = mid;
                }
            }

            return left - 1;
        }
    }
}