我试着自己解决这个问题,但过了一会儿就卡住了,所以看了看解决方案。这就是我得到的。
#include <stdio.h>
int main(void)
{
char str[] =
"73167176531330624919225119674426574742355349194934"
"96983520312774506326239578318016984801869478851843"
"85861560789112949495459501737958331952853208805511"
"12540698747158523863050715693290963295227443043557"
"66896648950445244523161731856403098711121722383113"
"62229893423380308135336276614282806444486645238749"
"30358907296290491560440772390713810515859307960866"
"70172427121883998797908792274921901699720888093776"
"65727333001053367881220235421809751254540594752243"
"52584907711670556013604839586446706324415722155397"
"53697817977846174064955149290862569321978468622482"
"83972241375657056057490261407972968652414535100474"
"82166370484403199890008895243450658541227588666881"
"16427171479924442928230863465674813919123162824586"
"17866458359124566529476545682848912883142607690042"
"24219022671055626321111109370544217506941658960408"
"07198403850962455444362981230987879927244284909188"
"84580156166097919133875499200524063689912560717606"
"05886116467109405077541002256983155200055935729725"
"71636269561882670428252483600823257530420752963450";
size_t len = sizeof str - 1;
size_t i;
unsigned max = 0;
for (i = 0; i < len-4; i++) {
unsigned p = 1;
size_t j;
for (j = 0; j < 5; j++) {
p *= (unsigned)(str[i+j]-'0');
}
if (p > max) {
max = p;
}
}
printf("%u\n", max);
return 0;
}
我的问题:我不明白为什么这一行有-'0'
p *= (unsigned)(str[i+j]-'0');
对不起,如果我的问题很愚蠢。但我好像想不出来。
最佳答案
'0' - '0' == 0
'1' - '0' == 1
'2' - '0' == 2
etc.
基本上,它是用来把a
char
转换成相应的数字。一种解释是字符直接映射到ASCII值:
'0' == 48
'1' == 49
'2' == 50
etc.
这些值是连续的。因此,当您减去最低的数字时,您将得到该数字之后的位置,这也是该数字的整数值。
关于c - 欧拉计划#8,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/20710051/