Question

我最近一直在研究Euler项目。我在C编程并有一个与问题8相关的查询。问题是：

Find the greatest product of five consecutive digits in the 1000-digit number.

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

这是我自己完成的工作：

#include <stdio.h>
#include <string.h>

int main(void)
{
    char *string = "731671765313306249192251196744.............";
    char *x;
    x = string;
    for(int counter = 0;counter < 2;counter++)
    {
        printf("%s\n", x + strlen(x) - 5);
        x = x + strlen(x) - 5;
    }
}

所以，问题在于无法理解下一步该做什么。我能够提取数字，但是使用这些数字的算法是什么，并创建一个快速有效的算法。所以，请帮忙！另一个问题是，当我尝试将char转换为int值时，它会失败并提供错误＆＃34;错误：指向整数转换的不兼容指针初始化＆＃39; char＆＃39;表达式为＆＃39; char [1001]＆＃39;。我已经使用这些方法将值转换为这里：Coversion of char to int，就这样吧。如果有更多建议，请提出更好的建议......

Answer 1

您可以读取字符串中的字符，将它们转换为整数，然后找到它们的产品，以检查哪组5个连续整数给出最高的产品。失去乐趣和学习，你可以尝试自己做，你可以试试这个。

#include <stdio.h>
#include <string.h>

// calculates the product of a group of numeric chars
// after converting them to int type
int gproduct(char *s, int glen) {
    int i = 0;
    int val = 1;

    // convert a numeric char to int value by subtracting '0'
    // assuming the chars are encoded in ascii. consider using
    // the standard library function atoi for portability.
    while(i < glen)
        val *= (s[i++] - '0');  

    return val;
}

int main(void) {
    char *numstr = "731671765313306249192251196744.............";
    int glen = 5;  // group length
    int maxcount = strlen(numstr) - glen;  
    int maxval = gproduct(numstr, glen);  // initialize maxval
    int tempval;
    for(int i = 1; i < maxcount; i++) {
        tempval = gproduct(numstr + i, glen);
        if(tempval > maxval) 
            maxval = tempval;  
    }
    printf("%d\n", maxval);
    return 0;
}

Euler项目中的问题＃8

1 个答案: