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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#101588 | #5. 在线 O(1) 逆元 | NOI_AK_ME | 100 ✓ | 1927ms | 19708kb | C++20 | 1.5kb | 2023-04-30 13:47:52 | 2024-11-05 21:48:54 |
Judging History
你现在查看的是最新测评结果
- [2023-08-10 23:21:45]
- System Update: QOJ starts to keep a history of the judgings of all the submissions.
- [2023-04-30 13:47:52]
- 提交
answer
#pragma once
#pragma GCC optimize("Ofast, unroll-loops")
#include<bits/stdc++.h>
#include"inv.h"
using std::cin;
using std::cout;
const int mod = 998244353;
const int mod2 = 974849;
const int w = sqrt(mod2);
const int limit = 3 * (w + 1) * 1024;
int djq[limit], arr[mod2];
using u64 = unsigned long long;
int inv(int x) {
const int p = (u64) x * arr[x >> 10] % mod;
return (u64) arr[x >> 10] * (p < limit ? djq[p] : mod - djq[mod - p]) % mod;
}
void init(int) {
for(int i = w;i >= 1;--i) {
std::function<int(int)> getinv = [&](int x) {
return x == 1 ? 1 : mod2 - u64(mod2 / x) * getinv(mod2 % x) % mod2;
};
int inv = getinv(i);
for(int j = 1;j <= w;++j) {
arr[(u64) j * inv % mod2] = i;
arr[mod2 - (u64) j * inv % mod2] = mod - i;
}
}
arr[0] = 1;
// 0 <= x * arr[x] - k * mod2 < w, and arr[x] < w, k < w
// 998244353 = mod2 * 1024 - 1023
// 0 <= 1024x * arr[x] - k * 998244353 < w * 1024 + 1023 * k
// 0 <= (1024x + y) * arr[x] - k * 998244353 < w * 1024 + 1023 * k + 1024 * w
djq[1] = 1;
// 等下再优化这个
for(int i = 2;i < limit;++i) {
djq[i] = mod - u64(mod / i) * djq[mod % i] % mod;
}
}
/*
int main() {
std::ios::sync_with_stdio(false), cin.tie(0);
init();
for(int i = 1;i < mod;++i) {
if(u64(getinv(i)) * i % mod != 1) {
cout << getinv(i) << ' ' << i << '\n';
return 0;
}
if(i % 300000 == 0) {
std::cerr << "debug : " << i << std::endl;
}
}
}
*/
Details
Pretests
Final Tests
Test #1:
score: 10
Accepted
time: 13ms
memory: 19460kb
Test #2:
score: 20
Accepted
time: 207ms
memory: 19360kb
Test #3:
score: 30
Accepted
time: 967ms
memory: 19420kb
Test #4:
score: 20
Accepted
time: 1537ms
memory: 19384kb
Test #5:
score: 20
Accepted
time: 1927ms
memory: 19708kb