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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#762723 | #8023. The Journey of Geor Autumn | yyx | RE | 0ms | 0kb | C++14 | 889b | 2024-11-19 16:23:31 | 2024-11-19 16:23:37 |
Judging History
answer
#include<bits/stdc++.h>
#define int long long
using namespace std;
const int MAXN = 1e7 + 10;
const int mod = 998244353;
int n, k;
int dp[MAXN], sum[MAXN];
int fac[MAXN], inv[MAXN];
int qpow(int a, int b){ int res = 1; for(; b; b >>= 1, a = a * a % mod) if(b & 1) res = res * a % mod; return res; }
signed main(){
freopen("b.in", "r", stdin);
freopen("b.out", "w", stdout);
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> n >> k; dp[0] = sum[0] = 1;
fac[0] = 1; for(int i = 1; i <= n; ++i) fac[i] = fac[i - 1] * i % mod;
inv[n] = qpow(fac[n], mod - 2); for(int i = n - 1; i >= 0; --i) inv[i] = inv[i + 1] * (i + 1) % mod;
for(int i = 1; i <= n; ++i){
dp[i] = fac[i - 1] * (sum[i - 1] - (i <= k ? 0ll : sum[i - min(k, i) - 1]) + mod) % mod;
sum[i] = (sum[i - 1] + dp[i] * inv[i] % mod) % mod;
}
cout << dp[n];
return 0;
}
Details
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Test #1:
score: 0
Dangerous Syscalls
input:
1 1