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 Go (1.14.1) (judge verdict: Time Limit Exceeded)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var k int

const intmax = 300000 + 1

func main() {
	n := readI()
	k = readI()
	a := make([]int, n+1)
	for i := 1; i <= n; i++ {
		a[i] = readI()
	}

	// dp[i] = 最後にiを使用した際の部分列の最大長
	dp := make([]int, intmax)
	for i := 1; i <= n; i++ {
		m := 1
		for j := max(1, a[i]-k); j <= min(intmax-1, a[i]+k); j++ {
			m = max(m, dp[j]+1)
		}
		dp[a[i]] = m
	}
	fmt.Println(max(dp...))

}

func good(a, b int) bool {
	if abs(a-b) <= k {
		return true
	}
	return false
}

func abs(a int) int {
	if a < 0 {
		return -a
	}
	return a
}

func max(a ...int) int {
	m := a[0]
	for i := 1; i < len(a); i++ {
		if m < a[i] {
			m = a[i]
		}
	}
	return m
}

func min(a ...int) int {
	m := a[0]
	for i := 1; i < len(a); i++ {
		if m > a[i] {
			m = a[i]
		}
	}
	return m
}

/*-----------Input utils-----------*/

var sc = bufio.NewScanner(os.Stdin)

func init() {
	if len(os.Args) >= 2 {
		if os.Args[1] == "debug" {
			debug()
		}
	}
	const buf = 200100
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, buf), buf)
}

func debug() {
	testFile, err := os.Open("./test/sample-1.in")
	if err != nil {
		fmt.Fprintln(os.Stderr, "There is no testfile.")
		os.Exit(1)
	}
	sc = bufio.NewScanner(testFile)
}

func readS() string {
	sc.Scan()
	return sc.Text()
}

func readR() []rune {
	return []rune(readS())
}

func readI() int {
	i, _ := strconv.Atoi(readS())
	return i
}

func readF() float64 {
	f, _ := strconv.ParseFloat(readS(), 64)
	return f
}