QOJ.ac
QOJ
ID | 题目 | 提交者 | 结果 | 用时 | 内存 | 语言 | 文件大小 | 提交时间 | 测评时间 |
---|---|---|---|---|---|---|---|---|---|
#796123 | #9553. The Hermit | lew2018 | WA | 1303ms | 5940kb | C++14 | 1.6kb | 2024-12-01 12:20:33 | 2024-12-01 12:20:33 |
Judging History
answer
#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define For(i, a, b) for (int i = (a); i <= (b); i++)
#define FOR(i, a, b) for (int i = (a); i >= (b); i--)
#define int long long
const int N = 1e5 + 5;
const int mod = 998244353;
int n, m, cnt[N];
ll fac[N], inv[N], ans;
int qpow(int a, int b) {
int res = 1;
while (b) {
if (b & 1) res = (ll)res * a % mod;
a = (ll)a * a % mod;
b >>= 1;
}
return res;
}
// m个数里选n个
ll c(int m, int n) {
if (n == m) return 1;
if (n > m || n < 0) return 0;
return (fac[m] * inv[n] % mod * inv[m - n] % mod) % mod;
}
void dfs(int u, int len) {
//cout << "u = " << u << " len = " << len << endl;
if (len == n) {
ans -= 1;
return;
}
(ans -= c(cnt[u] - 1, n - len)) %= mod;
for (int j = 2 * u; j <= m; j += u) {
dfs(j, len + 1);
}
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
cin >> m >> n;
if (n == 1) {
cout << "0" << endl;
return 0;
}
fac[0] = 1;
For (i, 1, m) {
fac[i] = (ll)fac[i - 1] * i % mod;
inv[i] = qpow(fac[i], mod - 2);
}
For (i, 1, n) {
int tot = 0;
for (int j = i; j <= m; j += i) tot++;
cnt[i] = tot;
}
ans = c(m, n) * n % mod;
// 枚举删的第一个数
for (int i = 1; i <= m; i++) {
(ans -= c(cnt[i] - 1, n - 1)) %= mod;
// 枚举删的第二个数
for (int j = 2 * i; j <= m; j += i) {
dfs(j, 2);
}
}
cout << (ans + mod) % mod << endl;
return 0;
}
详细
Test #1:
score: 100
Accepted
time: 0ms
memory: 3696kb
input:
4 3
output:
7
result:
ok 1 number(s): "7"
Test #2:
score: 0
Accepted
time: 1ms
memory: 5720kb
input:
11 4
output:
1187
result:
ok 1 number(s): "1187"
Test #3:
score: 0
Accepted
time: 1303ms
memory: 5940kb
input:
100000 99999
output:
17356471
result:
ok 1 number(s): "17356471"
Test #4:
score: 0
Accepted
time: 32ms
memory: 3936kb
input:
11451 1919
output:
845616153
result:
ok 1 number(s): "845616153"
Test #5:
score: 0
Accepted
time: 1303ms
memory: 5264kb
input:
99998 12345
output:
936396560
result:
ok 1 number(s): "936396560"
Test #6:
score: 0
Accepted
time: 0ms
memory: 3680kb
input:
100000 1
output:
0
result:
ok 1 number(s): "0"
Test #7:
score: -100
Wrong Answer
time: 1302ms
memory: 5172kb
input:
100000 15
output:
580649349
result:
wrong answer 1st numbers differ - expected: '190067060', found: '580649349'