Prime no. between two nos

#1

i cant find a logic to do this other than this

#include<bits/stdc++.h>
using namespace std;
int main()
{
int t;
cin>>t;

while(t--)
{
    int pc=0;
    int a,b,j,i;
    cin>>a;
    cin>>b;
    if(a==1)
        a=a+1;
    for( i=a;i<=b;i++)
    {

        for( j=2;j<i;j++)
        {

            if(i%j==0)
                break;
        }
        if(j==i)
            pc++;
    }
    cout<<pc<<endl;

}

}

please help me in this

#2

you need to learn sieve to find prime numbers in optimized way.
it is a part of Number theory.
After learning Sieve, you need to learn Segmented Sieve to find prime between to two numbers in more optimized way

#3

Hey Aman, as you are not responding to this thread, I am marking your doubt as Resolved for now. Re-open it if required. And please mark your doubts as resolved in your course’s “Ask Doubt” section, when your doubt is resolved.