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Project Euler #10: Summation of primes

Question
The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.
Find the sum of all the primes below two million.

Answer : 142913828922

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Solution


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import java.util.*;

public class Solution {
    public static void main(String[] args) {
        boolean arr[] = new boolean[10000000+1];
        for(int i=2;i<=10000000;i++){
            arr[i]=true;
        }
        for(int j=2;j*j<=10000000;j++){
            if(arr[j]){
                for(int k=j*2;k<=10000000;k+=j){
                    arr[k]=false;
                }
            }
        }
        long arr2[] = new long[10000000+1];
        long sum2=0;
        for(int f=2;f<=10000000;f++){
            if(arr[f]){
                sum2+=f;
            }
            arr2[f]=sum2;
        }
        Scanner in = new Scanner(System.in);
        int t = in.nextInt();
        for(int a0 = 0; a0 < t; a0++){
            int n = in.nextInt();
            System.out.println(arr2[n]);
        }
    }
}
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