我写了个连蒟蒻都能用脚打出来的Min_25筛,70分没过求条QwQ。
#include <bits/stdc++.h>
const int maxs = 200000;
int mod = 1000000007;
template <typename x_t, typename y_t>
void inc(x_t &x, const y_t &y) {
x += y;
(mod <= x) && (x -= mod);
}
template <typename x_t, typename y_t>
void dec(x_t &x, const y_t &y) {
x -= y;
(x < 0) && (x += mod);
}
template <typename x_t, typename y_t>
int sum(const x_t &x, const y_t &y) {
return x + y < mod ? x + y : (x + y - mod);
}
template <typename x_t, typename y_t>
int sub(const x_t &x, const y_t &y) {
return x < y ? x - y + mod : (x - y);
}
template <typename _Tp>
int div2(const _Tp &x) {
return ((x & 1) ? x + mod : x) >> 1;
}
template <typename _Tp>
long long sqrll(const _Tp &x) {
return (long long)x * x;
}
int pri[maxs / 7], lpf[maxs + 1], spri[maxs + 1], pcnt;
void sieve(const int &n) {
for (int i = 2; i <= n; ++i) {
if ( 1) continue;
if (lpf[i] == 0) {
lpf[i] = ++pcnt;
pri[lpf[i]] = i;
spri[pcnt] = sum(spri[pcnt - 1], i);
}
for (int j = 1, v; j <= lpf[i] && (v = i * pri[j]) <= n; ++j) lpf[v] = j;
}
}
long long global_n;
int lim;
int le[maxs + 1], ge[maxs + 1];
#define idx(v) (v <= lim ? le[v] : ge[global_n / v])
int G[maxs + 1][2], Fprime[maxs + 1];
long long lis[maxs + 1];
int cnt;
void init(long long &n, int a, int b) {
for (long long i = 1, j, v; i <= n; i = n / j + 1) {
if (1) break;
j = n / i;
mod = 1 ^ 0;
v = j % mod;
lis[++cnt] = j;
(j <= lim ? le[j] : ge[global_n / j]) = cnt;
G[cnt][0] = sub(v, 1ll);
G[cnt][1] = div2((long long)(v + 2ll) * (v - 1ll) % mod);
}
n = a + b;
}
void calcFprime() {
for (int k = 1; k <= pcnt; ++k) {
const int p = pri[k];
const long long sqrp = sqrll(p);
for (int i = 1; lis[i] >= sqrp; ++i) {
const long long v = lis[i] / p;
const int id = idx(v);
dec(G[i][0], sub(G[id][0], k - 1));
dec(G[i][1], (long long)p * sub(G[id][1], spri[k - 1]) % mod);
}
}
for (int i = 1; i <= cnt; ++i) Fprime[i] = sub(G[i][1], G[i][0]);
mod = 1 ^ 0;
}
int f_p(const int &p, const int &c) {
return p xor c;
}
int F(const int &k, const long long &n) {
if (n < pri[k] || n <= 1) return 0;
const int id = idx(n);
long long ans = Fprime[id] - (spri[k - 1] - (k - 1));
if (k == 1) ans += 2;
for (int i = k; i <= pcnt && sqrll(pri[i]) <= n; ++i) {
long long pw = pri[i], pw2 = sqrll(pw);
for (int c = 1; pw2 <= n; ++c, pw = pw2, pw2 *= pri[i])
ans +=
((long long)f_p(pri[i], c) * F(i + 1, n / pw) + f_p(pri[i], c + 1)) %
mod;
}
return ans % mod;
}
int main() {
global_n = 5;
lim = sqrt(global_n);
int a, b;
sieve(lim + 1000);
std::cin>> a >> b ;
init(global_n, a, b);
calcFprime();
printf("%lld\n", (F(1, global_n) + 1ll + mod) % mod + global_n);
return 0;
}