1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
|
// weighted_die.cpp
//
// Copyright (c) 2009
// Steven Watanabe
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//[weighted_die
/*`
For the source of this example see
[@boost://libs/random/example/weighted_die.cpp weighted_die.cpp].
*/
#include <boost/random/mersenne_twister.hpp>
#include <boost/random/discrete_distribution.hpp>
boost::mt19937 gen;
/*`
This time, instead of a fair die, the probability of
rolling a 1 is 50% (!). The other five faces are all
equally likely.
__discrete_distribution works nicely here by allowing
us to assign weights to each of the possible outcomes.
[tip If your compiler supports `std::initializer_list`,
you can initialize __discrete_distribution directly with
the weights.]
*/
double probabilities[] = {
0.5, 0.1, 0.1, 0.1, 0.1, 0.1
};
boost::random::discrete_distribution<> dist(probabilities);
/*`
Now define a function that simulates rolling this die.
*/
int roll_weighted_die() {
/*<< Add 1 to make sure that the result is in the range [1,6]
instead of [0,5].
>>*/
return dist(gen) + 1;
}
//]
#include <iostream>
int main() {
for(int i = 0; i < 10; ++i) {
std::cout << roll_weighted_die() << std::endl;
}
}
|
