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Diego Murray
2,515 PointsProject Euler Problem 10 JAVA - Bug
Not sure why I don't get the right answer here...
public class Main {
public static final int num = 2000000;
public static void main(String[] args) {
int sum = 0;
for (int i = 0; i < num; i++) {
if(isPrime(i)) {
sum += i;
}
}
System.out.println("Sum: " + sum);
}
public static boolean isPrime(int n) {
if (n <= 1) {
return false;
}
for (int i = 2; i < Math.sqrt(n); i++) {
if (n % i == 0) {
return false;
}
}
return true;
}
}
1 Answer
Simon Coates
28,695 PointsWorking on sums of primes under 10. Starting small so numbers are manageable.
public class Main {
public static final int num = 10;
public static void main(String[] args) {
int sum = 0;
for (int i = 0; i < num; i++) {
if(isPrime(i)) {
sum += i;
System.out.println("Prime:"+i);
}
}
System.out.println("Sum: " + sum);
}
public static boolean isPrime(int n) {
if (n <= 1) {
return false;
}
for (int i = 2; i < Math.sqrt(n); i++) {
if (n % i == 0) {
return false;
}
}
return true;
}
}
produces
Prime:2
Prime:3
Prime:4
Prime:5
Prime:7
Prime:9
Sum: 30
I'm guessing
public class Main {
public static final int num = 10;
public static void main(String[] args) {
int sum = 0;
for (int i = 0; i < num; i++) {
if(isPrime(i)) {
sum += i;
System.out.println("Prime:"+i);
}
}
System.out.println("Sum: " + sum);
}
public static boolean isPrime(int n) {
if (n <= 1) {
return false;
}
for (int i = 2; i <= Math.sqrt(n); i++) {
if (n % i == 0) {
return false;
}
}
return true;
}
}
Diego Murray
2,515 PointsI see now that it's collecting numbers that aren't Primes( ex. 2, 4). You posted the same code again, not sure if that was intentional..
Simon Coates
28,695 Pointsthere was a difference in the isPrime method. <= not <
Diego Murray
2,515 PointsI see now. Thank you
Diego Murray
2,515 PointsDiego Murray
2,515 PointsLooking for sum of all primes under 2 million.