Question

我试图找到甚至斐波纳契数的总和，直到400万。我找到了这些数字，但我无法将它们加起来......在if（n％2 == 0）循环中

 public static void number2()
 {
    int number = 40;
    int a, b, c;
    int numLim = 0;
     a = 1;
     b = 2;

    while(numLim < 4000000)
    {
        c = a + b;
        a = b;
        b = c;
        numLim = b;
        if(numLim > 4000000)
        {
             break;
        }
        int sum = 0;
        if(numLim % 2 == 0)
        { 
            System.out.println(numLim);
            sum = sum + numLim;
            System.out.println("sum :" +sum);
        }
    }
}

Answer 1

您必须在sum循环之外定义while，否则每次迭代都会变为0。

int sum = 0;
...
while ...

切记不要在每次迭代时将sum设置为0。

Answer 2

public class Euler2 {
public static void main(String[] args) {
    int fibonacci;
    int num = 0;
    int num2 = 1;
    int loop;
    int sum = 0;
    System.out.println(num2);
        for (loop = 0; loop <= 32; loop++) {
            fibonacci = num + num2;
            num = num2;
            num2 = fibonacci;
            System.out.println("Fibonacci number : " + fibonacci);
        sum += fibonacci;
        System.out.println("This is the sum " +sum);
    }
}

}

所以我这样解决了它，它的效率更高，数学有效，但欧拉讨厌我，希望这会有所帮助。

Answer 3

public class Euler2 {
public static void main(String[] args) {
    int fibonacci;
    int num = 0;
    int num2 = 1;
    int loop;
    int sum = 0;
    System.out.println(num2);
        for (loop = 0; loop <= 31; loop++) {
            fibonacci = num + num2;
            num = num2;
            num2 = fibonacci;
            System.out.println("Fibonacci number : " + fibonacci);

            if (fibonacci%2 == 0) {
                sum += fibonacci;
                System.out.println(sum);
            }
        }
}

抱歉，此代码有效。

Answer 4

试图在Java中执行上述操作，这是我的解决方案

 public static void main(String[] args) {

        int first = 1;
        int second = 2;
        int sum = 0;
        int sumOfEvenValuedTerms = second;
        for (int i = 0; i < 30; i++) {
            sum = first + second;
            if (sum <= 4000000) {
                if (sum % 2 == 0) {
                    sumOfEvenValuedTerms += sum;
                }

                first = second;
                second = sum;
            }
        }
        System.out.println(sumOfEvenValuedTerms);
    }

输出为4613732

Answer 5

public static int getSumOfEvenNumbers(int n) {

        int prev = 0;

        int i =1;

        int sum = 0;

        while (i<n){


            int nextNumber = i + prev;

            if(nextNumber %2 ==0) {
                System.out.println(nextNumber);
                sum +=nextNumber;
            }



            prev = i;
            i = nextNumber;
        }

        return sum;

    }

Answer 6

public class evenFib {
    public static void main(String[] args) {
        double a = 1, b = 2, c = 0, sum = 0;
        for (double i = 0; i <= 1000; i++) {
            c = a + b;
            a = b;
            b = c;
            if (c % 2 == 0 && sum < 4000000) {
                sum = sum + c;

            }
        }
        System.out.println(sum + 2);

    }
}

试图找到甚至斐波纳契数的总和为400万

6 个答案: