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 Java (OpenJDK 11.0.6) (judge verdict: Wrong Answer)

import java.util.*;

public class Main {
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int k = sc.nextInt();
		int[] highes = new int[n + 1];
		int[] lowes = new int[n + 1];
		int max = 0;
		highes[0] = Integer.MAX_VALUE / 10;
		lowes[0] = Integer.MIN_VALUE / 10;
		for (int i = 0; i < n; i++) {
		    int x = sc.nextInt();
		    for (int j = max; j >= 0; j--) {
		        if (highes[j] + k >= x && lowes[j] - k <= x) {
		            if (j == max) {
		                highes[j + 1] = x;
		                lowes[j + 1] = x;
		                max++;
		            } else {
		                highes[j + 1] = Math.max(highes[j + 1], x);
		                lowes[j + 1] = Math.max(lowes[j + 1], x);
		            }
		            break;
		        }
		    }
		}
		System.out.println(max);
	}
}