代码如下

//
// Created by ymbdff on 2023.11.15
//
#include <iostream>
#include <ctime>
using namespace std;

#define LL unsigned long long
#define int unsigned int
const int MOD = 998244353;

static int n, k, i; LL ans;
inline int ksm(register LL a, register int p){
	register int temp = 1;
	for (; p; p >>= 1){
		if (p & 1) temp = (1ll * temp * a) % MOD;
		a *= a;a %= MOD;
	}
	// cout << (1ll * temp + k) % MOD;puts("");
	return temp;
}
signed main(){
	// freopen("E.out","w",stdout);
	ios::sync_with_stdio(false);
	cin >> n >> k;
	for (i = 1; i <= n; ++i){
		ans = ans xor (1ll * ksm((LL)(i), i) + k) % MOD;
	}
	cout << ans;
}
//19999983 986094939

数据规模 n\le 2e7，极限情况下跑了1.2秒，请问还能怎么优化