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IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#65812#4843. Infectious Diseaseclf123456RE 193ms301440kbC++201.2kb2022-12-03 18:29:402022-12-03 18:29:42

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.
  • [2022-12-03 18:29:42]
  • 评测
  • 测评结果:RE
  • 用时:193ms
  • 内存:301440kb
  • [2022-12-03 18:29:40]
  • 提交

answer

#include<bits/stdc++.h>
#define int long long

using namespace std;
const int maxn=1e7+5e6;
const int mod=1e9+7;
int jc[maxn],inv[maxn],n;
signed dp[1000000][16];
int mp[maxn];
int C(int n,int m){
	return jc[n]*inv[n-m]%mod*inv[m]%mod;
}
int ksm(int x,int p,int mod){
	int ans=1;
	while(p){
		if(p&1) ans=ans*x%mod;
		x=x*x%mod;
		p>>=1;
	}
	return ans;
}
int dfs(int x,int y){
	if(x==0) return 0;
	if(y!=1) assert(mp[y]);
	if(dp[x][mp[y]]!=-1) return dp[x][mp[y]];
	int r=min(2*x,n-y);
	int z=min(2*y,n-y);
	int sum=n-y;
	int mn=max(0LL,r+z-sum);
	int mx=min(r,z);
	int ans=1;
	int fm=ksm(C(n-y,z),mod-2,mod);
	for(int i=mn;i<=mx;i++){
		ans+=C(r,i)*C(n-y-r,z-i)%mod*dfs(r-i,z+y)%mod*fm%mod;
		ans%=mod;
	}
	return dp[x][mp[y]]=ans;
}
void init(){
	jc[0]=inv[0]=1;
	for(int i=1;i<maxn;i++) jc[i]=i*jc[i-1]%mod;
	inv[maxn-1]=ksm(jc[maxn-1],mod-2,mod);
	for(int i=maxn-2;i>=1;i--){
		inv[i]=(i+1)*inv[i+1]%mod;
	}
	mp[1]=0;
	int base=3;
	for(int i=1;;i++){
		if(base>=n){
			mp[n]=i;
			break;
		}
		mp[base]=i;
		base*=3;
		
	}
}
signed main(){
	memset(dp,-1,sizeof(dp));
	init();
	int base=1;
	cin>>n;
	cout<<dfs(1,1)<<endl;
	return 0;
} 

Details

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Test #1:

score: 100
Accepted
time: 193ms
memory: 301440kb

input:

2

output:

1

result:

ok 1 number(s): "1"

Test #2:

score: -100
Dangerous Syscalls

input:

114

output:


result: