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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 |
---|---|---|---|---|---|---|---|---|---|
#591530 | #8635. 圆 | xiay | 100 ✓ | 46ms | 199400kb | C++14 | 1.3kb | 2024-09-26 16:19:06 | 2024-09-26 16:19:06 |
Judging History
answer
#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 5000 + 5, P = 998244353;
int dp[N][N];
int n;
long long fac[N];
long long qpow(long long a, int b) {
long long ans = 1;
while (b) {
if (b & 1) {
ans = ans * a % P;
}
a = a * a % P;
b >>= 1;
}
return ans;
}
void init() {
fac[0] = 1;
for (int i = 1; i <= n; i++) {
fac[i] = fac[i - 1] * i % P;
}
}
long long C(int n, int m) {
return fac[n] * qpow(fac[n - m], P - 2) % P * qpow(fac[m], P - 2) % P;
}
signed main() {
#ifndef ONLINE_JUDGE
freopen("test.in", "r", stdin);
freopen("test.out", "w", stdout);
#endif
scanf("%lld", &n);
if (n == 3) {
puts("1");
return 0;
}
init();
dp[0][0] = 1;
dp[1][1] = 1;
for (int i = 2; i < n; i++) {
for (int j = 1; j <= n; j++) {
dp[i][j] = dp[i - 1][j - 1];
if (i == 2) {
(dp[i][j] += dp[i - 2][j - 1]) %= P;
}
else {
(dp[i][j] += (dp[i - 2][j - 1] + dp[i - 3][j - 1]) % P) %= P;
}
}
}
int ans = 2;
for (int i = 1; i < n; i++) {
ans = (ans + 1ll * (C(n - 1, i) - (dp[n - 1][i] + dp[n - 2][i] + dp[n - 3][i]) % P + P) % P * fac[i] % P * fac[n - i - 1] % P * qpow(fac[n - 1], P - 2) % P) % P;
}
printf("%lld\n", ans);
return 0;
}
详细
Pretests
Final Tests
Test #1:
score: 10
Accepted
time: 0ms
memory: 3784kb
input:
3
output:
1
result:
ok 1 number(s): "1"
Test #2:
score: 10
Accepted
time: 0ms
memory: 3808kb
input:
4
output:
2
result:
ok 1 number(s): "2"
Test #3:
score: 10
Accepted
time: 1ms
memory: 5852kb
input:
6
output:
299473309
result:
ok 1 number(s): "299473309"
Test #4:
score: 10
Accepted
time: 0ms
memory: 3948kb
input:
10
output:
487238321
result:
ok 1 number(s): "487238321"
Test #5:
score: 10
Accepted
time: 1ms
memory: 8064kb
input:
100
output:
41620761
result:
ok 1 number(s): "41620761"
Test #6:
score: 10
Accepted
time: 1ms
memory: 10344kb
input:
200
output:
208771764
result:
ok 1 number(s): "208771764"
Test #7:
score: 10
Accepted
time: 0ms
memory: 24456kb
input:
500
output:
888621375
result:
ok 1 number(s): "888621375"
Test #8:
score: 10
Accepted
time: 45ms
memory: 192416kb
input:
4798
output:
319137015
result:
ok 1 number(s): "319137015"
Test #9:
score: 10
Accepted
time: 46ms
memory: 199344kb
input:
4999
output:
818467659
result:
ok 1 number(s): "818467659"
Test #10:
score: 10
Accepted
time: 45ms
memory: 199400kb
input:
5000
output:
142907477
result:
ok 1 number(s): "142907477"