ALCDC D問題 解答

ALCBC_D.gyp

import sys
def input(): return sys.stdin.readline().rstrip()
from fractions import gcd
class seg():
    def __init__(self,init_val):
        self.n=len(init_val)
        self.ide_ele= 0 #単位元
        self.num=2**(self.n-1).bit_length() #n以上の最小の2のべき乗
        self.seg=[self.ide_ele]*2*self.num
        for i in range(self.n):
            self.seg[i+self.num-1]=init_val[i]
        for i in range(self.num-2,-1,-1):
            self.seg[i]=self.seg_func(self.seg[2*i+1],self.seg[2*i+2])
    def seg_func(self,a,b):
        #return a+b #0
        #return a*b #1
        #return gcd(a,b) #0
        return max(a,b) #0か-1か-10**10 (十分小さいもの，計算に使う場合0)
        #return min(a,b) #10**10 (十分大きいもの)
    def update(self,k,x):
        k+=self.num-1
        self.seg[k]=x
        while k:
            k=(k-1)//2
            self.seg[k]=self.seg_func(self.seg[k*2+1],self.seg[k*2+2])
    def query(self,p,q): #O(logN)
        if q<=p:return self.ide_ele
        p+=self.num-1
        q+=self.num-2
        self.res=self.ide_ele
        while q-p>1:
            if p&1==0:
                self.res=self.seg_func(self.res,self.seg[p])
            if q&1==1:
                self.res=self.seg_func(self.res,self.seg[q])
                q-=1
            p=p//2
            q=(q-1)//2
        if p==q:self.res=self.seg_func(self.res,self.seg[p])
        else:self.res=self.seg_func(self.seg_func(self.res,self.seg[p]),self.seg[q])
        return self.res

def main():
    n, k = map(int,input().split())
    A = [int(input())for _ in range(n)]
    max_a = max(A)
    A_len = [0] * (max_a + 1) # 最後の数字がiのときの最大長さ
    SEG = seg(A_len)
    for a in A:
        SEG.update(a, SEG.query(max(a - k, 0), min(a + k, max_a) + 1) + 1)
    print(SEG.query(0, max_a + 1))

if __name__=='__main__':
    main()