typedef long long ll;
#define FR(i,a,b) for(int i=(a);i<(b);i++)
const int MAX=1e6+5;
int n=0,i=0,j=0;
int s[MAX];
void fil()
{
FR(i,1,MAX)s[i]=1;
for(i=2;i<MAX;i++)
{
for(j=i;j<MAX;j+=i)
s[j]+=i;
}
}
void solve()
{
while (1)
{
cin>>n;
if(n==0)return;
FR(i,1,MAX)
if(s[i]==n)
{
cout<<i<<"\n";
n=-1;
break;
}
if(n!=-1)cout<<"-1\n";
}
}
signed main()
{
fil();
solve();
return 0;
}
hey @yaduvanshii092 your code isn’t readable here
You can share this code using ide.codingblocks.com
your logic is correct to calculate seive, but in main function what you are computing is taking time. Now do what , since you have Find all the primes till 10^5 using seive. Now find sum of factors of numbers using prime numbers and (Mathematical formula sum of factors) Now for every test case simply check if it exist in array or not.
like this
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