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package ProjectEuler;

/**

* The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.

*

* <p>Find the sum of all the primes below two million.

*

* <p>link: https://projecteuler.net/problem=10

*/

public class Problem10 {

public static void main(String[] args) {

long[][] testNumbers = {

{2000000, 142913828922L},

{10000, 5736396},

{5000, 1548136},

{1000, 76127},

{10, 17},

{7, 10}

};

for (long[] testNumber : testNumbers) {

assert solution1(testNumber[0]) == testNumber[1];

}

}

/***

* Checks if a number is prime or not

* @param n the number

* @return {@code true} if {@code n} is prime

*/

private static boolean isPrime(int n) {

if (n == 2) {

return true;

}

if (n < 2 || n % 2 == 0) {

return false;

}

for (int i = 3, limit = (int) Math.sqrt(n); i <= limit; i += 2) {

if (n % i == 0) {

return false;

}

}

return true;

}

private static long solution1(long n) {

long sum = 0;

for (int i = 2; i < n; ++i) {

if (isPrime(i)) {

sum += i;

}

}

return sum;

}

}