Question

我目前正在使用Project Euler＃8。当我运行编译并运行下面的代码时，我得到：

Biggest product is 2090188800

这是不正确的。知道我做错了什么吗？必须与我所写的逻辑有关，但我不能为我的生活找出我错误的步骤。

//find greatest product generated by 13 consecutive integers below

class project_euler8 {

    public static final int LENGTH = 13;

    public static String numbers = 
    "73167176531330624919225119674426574742355349194934" +
    "96983520312774506326239578318016984801869478851843" +
    "85861560789112949495459501737958331952853208805511" +
    "12540698747158523863050715693290963295227443043557" +
    "66896648950445244523161731856403098711121722383113" +
    "62229893423380308135336276614282806444486645238749" +
    "30358907296290491560440772390713810515859307960866" +
    "70172427121883998797908792274921901699720888093776" +
    "65727333001053367881220235421809751254540594752243" +
    "52584907711670556013604839586446706324415722155397" +
    "53697817977846174064955149290862569321978468622482" +
    "83972241375657056057490261407972968652414535100474" +
    "82166370484403199890008895243450658541227588666881" +
    "16427171479924442928230863465674813919123162824586" +
    "17866458359124566529476545682848912883142607690042" +
    "24219022671055626321111109370544217506941658960408" +
    "07198403850962455444362981230987879927244284909188" +
    "84580156166097919133875499200524063689912560717606" +
    "05886116467109405077541002256983155200055935729725" +
    "71636269561882670428252483600823257530420752963450"; 

    public static int calculateProduct(char[] myArray) {
        int product = 1;
        for (int i = 0; i < myArray.length; i++) {
            int number = myArray[i] - '0';
            product *= number;
        }
        return product;
    }

    public static void main(String[] args) {

        //declare biggest_product, temporary array
        int biggest_product = 0;
        char[] temp = new char[LENGTH];

        //loop through each sequence of 13 integers
        for (int starting_index = 0; starting_index < numbers.length() - LENGTH; starting_index++) {
            for (int i = 0; i < LENGTH; i++) {
                temp[i] = numbers.charAt(starting_index + i);
            }
            int candidate_product = calculateProduct(temp);
            biggest_product = Math.max(candidate_product, biggest_product);
            starting_index++;
        }
        System.out.println("Biggest product is " + biggest_product);
    }
}

感谢您的帮助， Mariogs

Answer 1

Project Euler Problem 8州：

1000位数字中具有最大乘积的四个相邻数字是9×9×8×9 = 5832.

73167176531330624919225119674426574742355349194934   96983520312774506326239578318016984801869478851843   85861560789112949495459501737958331952853208805511   12540698747158523863050715693290963295227443043557   66896648950445244523161731856403098711121722383113   62229893423380308135336276614282806444486645238749   30358907296290491560440772390713810515859307960866   70172427121883998797908792274921901699720888093776   65727333001053367881220235421809751254540594752243   52584907711670556013604839586446706324415722155397   53697817977846174064955149290862569321978468622482   83972241375657056057490261407972968652414535100474   82166370484403199890008895243450658541227588666881   16427171479924442928230863465674813919123162824586   17866458359124566529476545682848912883142607690042   24219022671055626321111109370544217506941658960408   07198403850962455444362981230987879927244284909188   84580156166097919133875499200524063689912560717606   05886116467109405077541002256983155200055935729725   71636269561882670428252483600823257530420752963450

查找具有最大产品的1000位数字中的13个相邻数字。这个产品有什么价值？

在您的实现中找到解决方案，问题是您使用int来存储数字的乘积，这些数字将溢出。举一个例子，最大可能值是13个连续9的乘积，结果将是9 ^ 13 = 2541865828329，大于2 ^ 31 - 1（2147483647）。

使用long来存储数字产品的结果：

public static long calculateProduct(char[] myArray) {
    long product = 1;
    for (int i = 0; i < myArray.length; i++) {
        long number = myArray[i] - '0';
        product *= number;
    }
    return product;
}

Answer 2

您将starting_index增加两次，以便您跳过其他号码。

坚持项目欧拉＃8

2 个答案: