Question

我几个小时以来一直在修补这些代码，而我却无法输出正确的答案。谁能告诉我哪里出错？此版本正在输出104033

package Euler;

public class prime100001 {

    private static boolean isPrime(long num) {
        if (num == 2 || num == 3){
           return true;
        }
        if (num % 2 == 0){ 
            return false;
        }
        for (int i = 3; i * i < num; i += 2){
            if (num % i == 0){ 
                return false;
            }
        }
        return true;
    }

    public static void main (String [] args){

        int counter = 0;
        int primenum = 1;

        while(counter < 10001){
            primenum += 2;
            if(isPrime(primenum)){
                counter ++;
            }
        }
        System.out.println(primenum);
    }

}

Answer 1

只是想确定，你想打印10,001个素数吗？

public class prime100001 {
    private static boolean isPrime(long num) {
        if (num == 2 || num == 3){
            return true;
        }
        if (num % 2 == 0){
            return false;
        }
        for (int i = 3; (i * i) <= num; i += 1){
            // Changed the condition from < to <=, as you need to capture squares 
            // (e.g. when num = 9, original method will return false as i * i = 9 < 9 is false.
            // Also changed the increment from 2 to 1.
            if (num % i == 0){
                return false;
            }
        }
        return true;
    }

    public static void main(String [] args){

        int counter = 0;

        int lastPrime = 1;
        while(counter < 10001){
            lastPrime += 1;
            // Changed increment to include 2 in the count, plus
            // not skipping any other ints to test.
            if (isPrime(lastPrime)){
                counter++;
            }
        }
        System.out.println(lastPrime);
        // Shows 104,743
        // 10,000th prime: https://primes.utm.edu/lists/small/10000.txt
    }
}

希望这会有所帮助。 ;）

项目欧拉7 - 我完全陷入困境，无法弄明白

1 个答案: