I was trying to solve problem '1234 - Harmonic Number', I wrote the following code
long long H( int n ) {
long long res = 0;
for( int i = 1; i <= n; i++ )
res = res + n / i;
return res;
}
Yes, my error was that I was using the integer divisions only. However, you are given n, you have to find H(n) as in my code.
Input
Input starts with an integer T (≤ 1000), denoting the number of test cases.
Each case starts with a line containing an integer n (1 ≤ n < 231).
Output
For each case, print the case number and H(n) calculated by the code.
Sample Input
11
1
2
3
4
5
6
7
8
9
10
2147483647
Sample Output
Case 1: 1
Case 2: 3
Case 3: 5
Case 4: 8
Case 5: 10
Case 6: 14
Case 7: 16
Case 8: 20
Case 9: 23
Case 10: 27
Case 11: 46475828386
#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define ll long long
#include<cmath>
using namespace std;
int t;
ll n;
int main()
{scanf("%d",&t);
int w=0;
while(t--)
{w++;
scanf("%lld",&n);
int k=sqrt(n);
ll ans=0;
for(int i=1;i<=k;i++)
ans+=n/i;
for(int i=1;i<=k;i++)
ans+=((n/i)-(n/(i+1)))*i;
if(n/k==k)
ans-=k;
printf("Case %d: %lld\n",w,ans);
}
return 0;
}