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## Discussion of Problem 1118. Nontrivial Numbers

Why wa 11??
Posted by wiwi 19 Nov 2020 04:28
----
ll l,r;
cin >> l >> r;
if(l==1){
cout << 1;
return 0;
}
if(l == r){
cout << l;
return 0;
}
ll n = 1e6+2;
vector<bool> prime(n+1,1);
prime[0]=prime[1] = 0;
for( ll i =2; i*i <= n; i++)
{
if(prime[i])
{
for(ll j = i*i; j <= n; j+=i)
prime[j]=0;
}
}

for(ll i = r; i >= l; i--){
if(prime[i])
{

cout << i;
return 0;
}
}
double mx =1e11;
ll ans = 0;
for(ll i = r; i >= l; i--){

if(i % 2 == 0)
continue;

double suma = 1;
for(ll k = 2; k*k <= i; k++){

if( i % k == 0 ){
suma += k;
if(i/k != k){

suma += (i/k);
}
}
}

double q=(suma)/(i);

if( q < mx){
mx = q;
ans = i;
}

}
cout << ans;
return 0;
----

I used the sieve of Eratosthenes to find prime numbers. If I have not found prime numbers on the interval [l; r], then I iterate over all numbers with [l; r]. I go through the divisors (sqrt (i)). I calculate the minimum. What's wrong? WA 11. Google translator, sorry.