What wrong in this code same Got accepted on codeforces but not here

#1

#include
#include
#include
using namespace std;
typedef long double ll;

const int MAX=1e6+5;

ll last[MAX];
int a[MAX];
ll ans[MAX];

int main() {

long long n;	cin>>n;
memset(last,0,sizeof(last));
memset(ans,0,sizeof(ans));
for(int i=1;i<=n;i++)cin>>a[i];
ll sum=0.0;
for(int i=1;i<=n;i++)
{
	ans[i]=ans[i-1]+(i-last[a[i]]);
	last[a[i]]=i;
}

for(int i=1;i<=n;i++)
sum+=ans[i];

cout<<fixed<<setprecision(7);
sum=(2*sum-n)/(n*n);
cout<<sum;
return 0;

}

#2

@yaduvanshii092 there are precession issue with doubles and float change setprecission(7) to 6 it works

#3

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