Problem:
Score : 400 points

Problem Statement

You are given a sequence A_1, A_2, ..., A_N and an integer K.

Print the maximum possible length of a sequence B that satisfies the following conditions:

B is a (not necessarily continuous) subsequence of A.

For each pair of adjacents elements of B, the absolute difference of the elements is at most K.

Constraints

1 \leq N \leq 300,000

0 \leq A_i \leq 300,000

0 \leq K \leq 300,000

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N K
A_1
A_2
:
A_N

Output

Print the answer.

Sample Input 1

10 3
1
5
4
3
8
6
9
7
2
4

Sample Output 1

7

For example, B = (1, 4, 3, 6, 9, 7, 4) satisfies the conditions.

It is a subsequence of A = (1, 5, 4, 3, 8, 6, 9, 7, 2, 4).

All of the absolute differences between two adjacent elements (|1-4|, |4-3|, |3-6|, |6-9|, |9-7|, |7-4|) are at most K = 3.

Solution in C# (.NET Core 3.1.201) (judge verdict: Wrong Answer)

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

namespace ConsoleApp3
{
    internal class Class2
    {
        //C
        //private static void Main(string[] args)
        //{
        //    var nm = Console.ReadLine().Split(" ").Select(int.Parse).ToArray();
        //    var n = nm[0];
        //    var m = nm[1];

        //    var abs = Enumerable.Range(0, m)
        //        .Select(_ =>
        //        {
        //            var ab = Console.ReadLine().Split(" ").Select(int.Parse).ToArray();
        //            return (A: ab[0], B: ab[1]);
        //        })
        //        .ToArray();

        //    foreach (var (a, b) in abs)
        //    {

        //    }
        //}

        //D
        private static void Main(string[] args)
        {
            var nk = Console.ReadLine().Split(" ").Select(int.Parse).ToArray();
            var n = nk[0];
            var k = nk[1];

            var aArray = Enumerable.Range(0, n)
                .Select(_ => int.Parse(Console.ReadLine()))
                .ToArray();
            var last = aArray[0];
            var currentIndex = 0;
            var list = new List<int> { 1 };

            foreach (var (a, index) in aArray.Skip(1).Select((x, i) => (x, i)))
            {
                if (Math.Abs(a - last) <= k)
                {
                    list[currentIndex] += 1;
                    last = a;
                }
                else if (index + 1 < aArray.Length)
                {
                    var next = aArray[index + 1];
                    if (Math.Abs(next - a) < Math.Abs(next - last))
                    {
                        last = a;
                    }
                }
            }

            Console.WriteLine(list.DefaultIfEmpty().Max());
        }
    }
}