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 Julia (1.4.0) (judge verdict: Wrong Answer)

function main()
    N,K = reads(Int,Int)
    as = readvec(Int, N)
    lasts = [as[1]]
    cs = [1]
    for i in 2:N
        f = true
        con = []
        for j in 1:length(lasts)
            if abs(as[i] - lasts[j]) <= K
                push!(con, j)
                if lasts[j] < as[i]
                    lasts[j] = as[i]
                end
                f = false
            end
        end
        if f
            push!(lasts, as[i])
            push!(cs, 1)
        else
            lasts[con[findmax(map(x -> cs[x], con))[2]]] = as[i]
            cs[con[1]] += 1
        end
    end
    println(maximum(cs))
end

import Base.parse
import Base.StringVector

parse(::Type{String},  str::AbstractString) = str
isdelim(x::UInt8, xs::Set{UInt8}) = x in xs
const delimset = Set([0x0a, 0x20])

function myreaduntil(s::IO, delims::Set{UInt8})::Vector{UInt8}
    out = StringVector(0)
    c::UInt8 = 0x00
    while !eof(s)
        c = read(s, UInt8)
        !isdelim(c, delims) && break
    end
    push!(out, c)
    eof(s) && return out
    while !eof(s)
        c = read(s, UInt8)
        isdelim(c, delims) && break
        push!(out, c)
    end
    return out
end

function readword(io::IO = stdin, delims = delimset)::String
    word = myreaduntil(io, delims)
    i = length(word)
    if i == 0 || word[i] != 0x0a
        return String(word)
    elseif i < 2 || word[i-1] != 0x0d
        return String(resize!(word,i-1))
    else
        return String(resize!(word,i-2))
    end
end

pread(ty) = parse(ty, readword())

reads(tys...)::Tuple{tys...} = Tuple{tys...}(pread(ty) for ty in tys)

function readvec(tys::Tuple , len::Signed)::Tuple{map(x -> Vector{x},tys)...}
    rv = Tuple{map(x -> Vector{x},tys)...}(Vector{ty}(undef,len) for ty in tys)
    for i in 1:len
        for j in 1:length(tys)
            @inbounds rv[j][i] = pread(tys[j])
        end
    end
    rv
end

readvec(ty::Type, len::Signed)::Vector{ty} = @inbounds ty[pread(ty) for i in 1:len]

function readmat(ty::Type, s...)::Matrix{ty}
    v = Matrix{ty}(undef, s...)
    @inbounds for i in 1:s[1]
        v[i,:] = readvec(ty, s[2])
    end
    v
end

main()