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- // 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;
- }
- }
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