Question

你会想帮助我解决以下问题吗? 感谢。

Question: The percentage of rolling 3 dices of face 6 in one go can be found out mathematically or simulation. The Monte Carlo method is a computer process to find out the solution of a problem by computer simulation. Write a program that roll three dices, calculate their sum, and find out the probability of rolling each possible outcome.

You are given a skeleton program q1dskeleton.c that generates the statistics of rolling a dice of six sides 10000 times. Modify the program so that it generates the statistics of the sum of rolling three six-sided dices. An example of the program output is given in the following. Note that because of the random nature of dice rolling.

Hint: Call rand() 每 throw一次,每 d一次。

Skeleton:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define SIZE 7

int main() {

  int face, roll, frequency[SIZE] = { 0 };

  srand( time(NULL) );

  for (roll = 1; roll <= 10000; roll++) {
    face = rand() % 6 + 1;
    ++frequency[face];
  }
  printf("%s%12s
", "Face", "Frequency");

  for (face = 1; face <= SIZE - 1; face++)
    printf("%4d%12d
", face, frequency[face]);
  getchar();
}

产出:

Face Frequency
3     49
4     129
5     276
6     481
7     669
8     994
9     1131
10    1213
11    1269
12    1197
13    962
14    707
15    464
16    268
17    144
18    47

Answer 1

Also, when calculating rand() you need to realize it is not all that random as we hope.

From the documentation at: http://www.cplusplus.com/reference/clibrary/cstdlib/rand/ "Notice though that this modulo operation does not generate a truly uniformly distributed random number in the span (since in most cases lower numbers are slightly more likely), but it is generally a good approximation for short spans."

为了取得更好的结果,最好在为大面积地区找到一种不同的公式方面做一些工作,这种模式更有可能产生随机结果。

For instance, for dice one you get a random number between 30 and 90 and the formula is (int)(((float)result - 30) / 10) + 0.5 or something along those lines.

那么,如果是这样的话,你就可以在500到500之间找到一个数字,并拿出另一个公式。

To make your homework assignment more interesting you could have a look at how different online casinos/poker rooms do this. http://www.fulltiltpoker.com/random-number-generator

Answer 2

显然,你必须增加<条码>SIZE,因为不再有6种可能性,但18种-Ill 包括不可能达到的总数1和2种,因为你的原始解决办法包括不可能达到的零值。

然后,你不要扔ice一个ice子,而是扔下了 3<>m>,然后添加了价值。类似(假体编码):

dice1 = first random number dice2 = second random number dice3 = third random number face = dice1 plus dice2 plus dice3

http://em>addition是你用来增加具体阵列内容的。

就奖金点而言,你可能避免印刷不可能的结果。这非常简单地修改了您的最后<代码>(>说明的起始点。

您所期望的比率为<代码>{1、3、6、10、15、21、25、27、25、21、15、10、6、3、1},因此“理想”产出应合理接近:

Face   Frequency
   3          46
   4         138
   5         277
   6         462
   7         694
   8         972
   9        1157
  10        1250
  11        1250
  12        1157
  13         972
  14         694
  15         462
  16         277
  17         138
  18          46

(even though that only adds up to 9992 samples - it s a crapshoot as to where the other eight show up).

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