题解：CF2025C New Game

const int N=2e5+5;
int n,k;
int a[N];
int q[N];
void solve(){
	cin>>n>>k;
	map<int,int> mp;
	rep(i,1,n){
		cin>>a[i];
		mp[a[i]]++;
	}
	sort(a+1,a+1+n);
	int m=unique(a+1,a+1+n)-(a+1);
	int hh=1,tt=0;
	int res=0,ans=0;
	rep(i,1,m){
		while(hh<=tt && a[i]!=a[q[tt]]+1) res-=mp[a[q[tt]]],tt--;
		q[++tt]=i;
		if(q[hh]<i-(k-1)) res-=mp[a[q[hh]]],hh++;
		res+=mp[a[q[tt]]];
		ans=max(ans,res);
	}
	cout<<ans;
}