Buggy python submission (verdict: Time Limit Exceeded):
def op(a,b):
    return max(a,b)

class segmentTree:
    def __init__(self,n,op,init_value):
        dataLen=1 << (n - 1).bit_length()
        self.data=[init_value]*(2*dataLen)
        self.op=op
        self.length=dataLen
    def getIdx(self,left,right):
        idxs=[]
        l=left
        r=right
        while True:
            idx=1
            valueL=0
            valueR=self.length-1
            while l!=valueL or valueR>=r:
                if l<=valueL+(valueR-valueL)//2:
                    valueR-=(valueR-valueL+1)//2
                    idx*=2
                else:
                    valueL+=(valueR-valueL+1)//2
                    idx=idx*2+1
            idxs.append(idx)
            if valueR==r or valueR==r-1 :
                break
            l=valueR+1
        return idxs
    def get(self,n):
        return self.data[self.getIdx(n,n+1)[0]]

    def set(self,n,value):
        idx1=self.getIdx(n,n+1)[0]
        self.data[idx1]=value
        while idx1!=1:
            idx2=idx1^1
            if idx1>idx2:
                idx1,idx2=idx2,idx1
            self.data[idx1//2]=self.op(self.data[idx1],self.data[idx2])
            idx1//=2
    def query(self,l,r):
        idxs=self.getIdx(l,r)
        ret=self.data[idxs[0]]
        for idx in idxs:
            ret=self.op(ret,self.data[idx])
        return ret


N,K=map(int,input().split())
A=[]
for i in range(N):
  A.append(int(input()))


seg = segmentTree(N, op, 0)

for i in A:
  l=min(N,max(0,i-K))
  r=max(0,min(N,i+K))
  v=seg.query(l,r+1)
  seg.set(i,v+1)
print(seg.query(0,N))

Fixed submission:
#####segfunc#####
def segfunc(x, y):
    return max(x,y)
#################

#####ide_ele#####
ide_ele = 0
#################

class SegTree:
    """
    init(init_val, ide_ele): 配列init_valで初期化 O(N)
    update(k, x): k番目の値をxに更新 O(logN)
    query(l, r): 区間[l, r)をsegfuncしたものを返す O(logN)
    """
    def __init__(self, init_val, segfunc, ide_ele):
        """
        init_val: 配列の初期値
        segfunc: 区間にしたい操作
        ide_ele: 単位元
        n: 要素数
        num: n以上の最小の2のべき乗
        tree: セグメント木(1-index)
        """
        n = len(init_val)
        self.segfunc = segfunc
        self.ide_ele = ide_ele
        self.num = 1 << (n - 1).bit_length()
        self.tree = [ide_ele] * 2 * self.num
        # 配列の値を葉にセット
        for i in range(n):
            self.tree[self.num + i] = init_val[i]
        # 構築していく
        for i in range(self.num - 1, 0, -1):
            self.tree[i] = self.segfunc(self.tree[2 * i], self.tree[2 * i + 1])

    def update(self, k, x):
        """
        k番目の値をxに更新
        k: index(0-index)
        x: update value
        """
        k += self.num
        self.tree[k] = x
        while k > 1:
            self.tree[k >> 1] = self.segfunc(self.tree[k], self.tree[k ^ 1])
            k >>= 1

    def query(self, l, r):
        """
        [l, r)のsegfuncしたものを得る
        l: index(0-index)
        r: index(0-index)
        """
        res = self.ide_ele

        l += self.num
        r += self.num
        while l < r:
            if l & 1:
                res = self.segfunc(res, self.tree[l])
                l += 1
            if r & 1:
                res = self.segfunc(res, self.tree[r - 1])
            l >>= 1
            r >>= 1
        return res


N,K=map(int,input().split())
A=[]
for i in range(N):
  A.append(int(input()))

N=300000
  
data = [0]*N
seg = SegTree(data, segfunc, ide_ele)

for i in A:
  l=min(N,max(0,i-K))
  r=max(0,min(N,i+K))
  v=seg.query(l,r+1)
  seg.update(i,v+1)

print(seg.query(0,N))