Käännöt

#include <bits/stdc++.h>
#define F first
#define S second
using namespace std;
typedef long long ll;
typedef long double ld;

const ll mod=1e9+7;
const ll ik=700000005;
ll dd[101010];
ll dd2[101010];
ll vv1[101010];
ll vv2[101010];

int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	string s;
	cin>>s;
	int n=s.size();
	if (n==1){
		cout<<s<<endl;
		return 0;
	}
	ll e=1;
	for (int i=n-1;i>=0;i--){
		vv1[i]=(e*(ll)(s[i]-'0'))%mod;
		vv2[n-i-1]=(e*(ll)(s[i]-'0'))%mod;
		e*=10ll;
		e%=mod;
	}
	ll k=1;
	ll k2=1;
	int p1=(n-1)/2;
	int p2=(n)/2;
	for (int i=-1;i<(int)n-1;i++){
		//cout<<p1<<" "<<p2<<endl;
		dd[i+1]+=k;
		dd[i+1]%=mod;
		dd[p1+1]+=mod-k;
		dd[p1+1]%=mod;
		dd[p2+1]+=mod-k;
		dd[p2+1]%=mod;
		if (i>-1){
			//cout<<"k2 "<<k2<<endl;
			dd2[i+1]+=k2;
			dd2[i+1]%=mod;
			dd2[p1+1]+=mod-k2;
			dd2[p1+1]%=mod;
			dd2[p2+1]+=mod-k2;
			dd2[p2+1]%=mod;
		}
		k*=10ll;
		k%=mod;
		k2*=ik;
		k2%=mod;
		if ((n+i)%2==0){
			p2++;
		}
		else{
			p1++;
		}
	}
	//cout<<(ik*vv2[1])%mod<<" "<<ik<<endl;
	ll d=dd[0];
	ll d2=dd2[0];
	ll kk=0;
	ll kk2=0;
	ll v=0;
	for (int i=0;i<n;i++){
		kk+=d;
		kk%=mod;
		kk2+=d2;
		kk2%=mod;
		v+=kk*vv1[i];
		//cout<<"kk2 "<<kk2<<" "<<vv2[i]<<" "<<(kk2*vv2[i])%mod<<endl;
		v+=kk2*vv2[i];
		v%=mod;
		//cout<<kk<<" "<<vv1[i]<<endl;
		d+=dd[i+1];
		d%=mod;
		d2+=dd2[i+1];
		d2%=mod;
	}
	//cout<<v<<endl;
	for (int i=0;i<n;i++){
		v+=((ll)i*(ll)(i+1)/(ll)2)*vv1[i];
		v%=mod;
		v+=((ll)(n-i-1)*(ll)(n-i)/(ll)2)*vv1[i];
		v%=mod;
	}
	cout<<v<<endl;
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED