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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#790017 | #9553. The Hermit | xiaozong85 | WA | 13ms | 10808kb | C++14 | 1.8kb | 2024-11-27 23:37:23 | 2024-11-27 23:37:26 |
Judging History
answer
#include <bits/stdc++.h>
typedef long long ll;
typedef unsigned long long ull;
#define inf 0x3f3f3f3f
#define rep(i, l, r) for (int i = l; i <= r; i++)
#define rep_(i, l, r) for (int i = l; i >= r; i--)
#define cy cout << "YES" << '\n'
#define cn cout << "NO" << '\n'
#define xx first
#define yy second
#define pb push_back
#define endl '\n'
const int N=1e5+10;
const int mod=998244353;
//#define int ll
using namespace std;
int T=1;
int dp[20][N];//长度为c,以x结尾的方案数
int n,m;
int addv(int x,int y){return (x+y>=mod)?(x+y-mod):(x+y);}
int subv(int x,int y){return (x>=y)?(x-y):(x-y+mod);}
void add(int& x,int y){x = addv(x,y);}
void sub(int& x,int y){x = subv(x,y);}
int qpow(int a,int n){
int res = 1; a%=mod;
while(n){
if(n&1)res = 1ll*res*a%mod;
n>>=1; a = 1ll*a*a%mod;
}
return res;
}
int qinv(int a){return qpow(a,mod-2);}
//
ll fac[N],rfac[N],ans;
int C(int n,int m){
if(n<m || m<0)return 0;
return 1ll*fac[n]*rfac[m]%mod*rfac[n-m]%mod;
}
void solve(){
cin>>m>>n;
//cout<<dp[4][8]<<endl;
fac[0] = 1; for(int i=1;i<=m;i++)fac[i] = 1ll*fac[i-1]*i%mod;
rfac[m] = qinv(fac[m]); for(int i=m-1;i>=0;i--)rfac[i] = 1ll*rfac[i+1]*(i+1)%mod;
rep(i,1,m)dp[1][i]=1;
rep(i,1,m){
for(int j=1;j<20;j++){
if(dp[j][i]){
int w=dp[j][i];
for(int k=2*i;k<=m;k+=i){
dp[j+1][k]+=w;
}
}
}
}
ans=1ll*C(m,n)*n%mod;
for(int j=1;j<=m;j++){
for(int i=1;i<20&&i<=n;i++){
if(dp[i][j]){
if(m/j<1)continue;
ans=(ans-(dp[i][j]*C(m/j-1,n-i)%mod))%mod;
//cout<<i<<" "<<j<<" "<<dp[i][j]<<" "<<ans<<endl;
}
}
}
cout<<(ans+mod)%mod<<endl;
}
int main(){
ios::sync_with_stdio(0);cin.tie(0);
//cin>>T;
while(T--){
solve();
}
return 0;
}
Details
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Test #1:
score: 100
Accepted
time: 1ms
memory: 5632kb
input:
4 3
output:
7
result:
ok 1 number(s): "7"
Test #2:
score: 0
Accepted
time: 1ms
memory: 5696kb
input:
11 4
output:
1187
result:
ok 1 number(s): "1187"
Test #3:
score: 0
Accepted
time: 13ms
memory: 10568kb
input:
100000 99999
output:
17356471
result:
ok 1 number(s): "17356471"
Test #4:
score: 0
Accepted
time: 2ms
memory: 6216kb
input:
11451 1919
output:
845616153
result:
ok 1 number(s): "845616153"
Test #5:
score: -100
Wrong Answer
time: 6ms
memory: 10808kb
input:
99998 12345
output:
542131975
result:
wrong answer 1st numbers differ - expected: '936396560', found: '542131975'