jakaria_hossain

codeforce - lucky sum

Jun 16th, 2019
100
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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3. #define fast()(ios_base::sync_with_stdio(false),cin.tie(NULL));
  4. #define pb push_back
  5. #define ll long long
  6. #define MAX 4444444445
  7. int main()
  8. {
  9. fast()
  10. vector<ll>v;
  11. v.pb(4);
  12. v.pb(7);
  13. for(int i=0;i<v.size();i++)
  14. {
  15. if(v[i]*10+4>MAX)break;
  16. else v.pb(v[i]*10+4);
  17. if(v[i]*10+7>MAX)break;
  18. else v.pb(v[i]*10+7);
  19. }
  20. ll sum=0,l,r;
  21. cin>>l>>r;
  22. while(l<=r)
  23. {
  24. ll pos=lower_bound(v.begin(),v.end(),l )- v.begin();
  25. if(v[pos]>r)sum+=(r-l+1)*v[pos];
  26. else sum+=(v[pos]-l+1)*v[pos];
  27. l=v[pos]+1;
  28. }
  29. cout<<sum<<endl;
  30. }
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