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  1. #include <bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. const int TO = (1e7);
  6.  
  7. int tests,current_case;
  8. int n;
  9. long long sum[TO + 7];
  10. int x,y;
  11.  
  12. inline void fill() {
  13.     int i,j;
  14.  
  15.     for(i=1;i<=TO;i++) {
  16.         for(j=i+i;j<=TO;j+=i) {
  17.             sum[j]+=i;
  18.         }
  19.     }
  20.     for(i=1;i<=TO;i++) {
  21.         if(sum[i]>=i) sum[i]-=i;
  22.         else sum[i]=i-sum[i];
  23.         sum[i]+=sum[i-1];
  24.     }
  25. }
  26.  
  27. int main() {
  28.     fill();
  29.  
  30.     scanf("%d %d", &x, &y);
  31.     printf("%lld\n", sum[y]-sum[x-1]);
  32.  
  33.     return 0;
  34. }
  35.  
Success #stdin #stdout 1.84s 81600KB
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https://ideone.com/wfThUU
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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