Prime Sum
Problem Statement
Given a range from l to r, Your task is to find the sum of the second last digit of the prime numbers between that range.
import java.io.*; // for handling input/output
import java.util.*; // contains Collections framework
// don't change the name of this class
// you can add inner classes if needed
class Main {
static int n = 100000;
static boolean isPrime[] = new boolean[n+1]; // O(n)
static void primeSeive(){
//bit arr
//assume all are primes
for(int i=0;i<=n;i++){
isPrime[i] = true;
}
//mark 0 and 1 as not prime
isPrime[0] = isPrime[1] = false;
int sqrt = (int)Math.sqrt(n);
// 2..sqrt(n)
for(int i=2;i<=sqrt;i++){
if(isPrime[i]){
for(int j=i*i;j<=n;j=j+i){
isPrime[j] = false;
}
}
}
}
public static void main (String[] args) {
Scanner sc = new Scanner(System.in);
int tc = sc.nextInt();
primeSeive();
for(int t=0;t<tc;t++){
int l = sc.nextInt();
int r = sc.nextInt();
int sum = 0;
for(int i=l;i<=r;i++){
if(i>=10 && isPrime[i]){
sum = sum + (i/10)%10;
}
}
System.out.println(sum);
}
// Your code here
}
}
