Problem 001
Link: https://www.hackerrank.com/contests/projecteuler/challenges/euler001/problem
int main(){
int t;
cin >> t;
for(int a0 = 0; a0 < t; a0++){
long long int n;
cin >> n;
n--;
long long int sum=0;
long long int n3=n/3;
long long int n5=n/5;
long long int n15=n/15;
long long int val3=3*(n3*(n3+1))/2;
long long int val5=5*(n5*(n5+1))/2;
long long int val15=15*(n15*(n15+1))/2;
sum = val3 + val5 - val15;
cout<<sum<<endl;
}
return 0;
}
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