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  1. #include <bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. #define ll long long
  6.  
  7. ll mod = 1e9+7;
  8. int main()
  9. {
  10.     int t;
  11.     cin>>t;
  12.     for(int i=1;i<=t;i++)
  13.     {
  14.         ll n;
  15.         cin>>n;
  16.         string s;
  17.         cin>>s;
  18.         ll res=0;
  19.         for(int j=0;j<s.size();j++)
  20.         {
  21.             ll a=j+1,b=n-j;
  22.             a*=(a+1LL);
  23.             a/=2LL;a--;
  24.             b*=(b+1LL);
  25.             b/=2LL;
  26.             a%=mod;b%=mod;
  27.             a+=b;
  28.             a%=mod;
  29.             a*=s[j];
  30.             a%=mod;
  31.             res+=a;
  32.             res%=mod;
  33.         }
  34.         printf("Case %d: %lld\n",i,res);
  35.     }
  36.  
  37. }
  38.  
Success #stdin #stdout 0s 15232KB
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stdin
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2
1
a
2
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stdout
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Case 1: 97
Case 2: 588
https://ideone.com/9IFmKA
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
public

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