4.Sieve of Eretosthenes.cpp

 #include <bits/stdc++.h>

#include <ext/pb_ds/assoc_container.hpp>

#include <ext/pb_ds/tree_policy.hpp>

using namespace std;

using namespace __gnu_pbds;

template <class type1>

#define ll long long int

#define endl "\n"

#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>

using ordered_multiset = tree <type1, null_type, less_equal <type1>, rb_tree_tag, tree_order_statistics_node_update>;

 //ordered_multiset <ll> kek;(declaration for multiorder set)

// ordered_set o_set;(declaration)

//kek.order_of_key(i);(strictly less then i for multi order set)

//o_set.order_of_key(5) ;(strictly less then i for multi order set)

#define yes cout << "YES\n"

#define no cout << "NO\n"

const ll mxN=1000000;

ll isPrime[mxN];

void sieve()

{

     isPrime[0]=1;

     isPrime[1]=1;

     for(ll i=2;i*i<=mxN;i++)

     {

         if(isPrime[i]==0)

         {

             for(ll j=i*i;j<=mxN;j+=i)

             {

                 isPrime[j]=1;

             }

         }

     }

}

int main()

{

     sieve();

    ios_base::sync_with_stdio(0);

    cin.tie(0);

    cout.tie(0);

   

     ll t;

     cin>>t;

     while(t--)

     {

        ll n;

        cin>>n;

        if(isPrime[n]==0)cout<<"yes\n";

        else cout<<"no\n";

     }

    return 0;

}