56 lines
1.3 KiB
C++
56 lines
1.3 KiB
C++
// weighted_die.cpp
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//
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// Copyright (c) 2009
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// Steven Watanabe
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//[weighted_die
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/*`
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For the source of this example see
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[@boost://libs/random/example/weighted_die.cpp weighted_die.cpp].
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*/
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#include <boost/random/mersenne_twister.hpp>
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#include <boost/random/discrete_distribution.hpp>
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boost::mt19937 gen;
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/*`
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This time, instead of a fair die, the probability of
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rolling a 1 is 50% (!). The other five faces are all
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equally likely.
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__discrete_distribution works nicely here by allowing
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us to assign weights to each of the possible outcomes.
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[tip If your compiler supports `std::initializer_list`,
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you can initialize __discrete_distribution directly with
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the weights.]
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*/
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double probabilities[] = {
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0.5, 0.1, 0.1, 0.1, 0.1, 0.1
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};
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boost::random::discrete_distribution<> dist(probabilities);
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/*`
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Now define a function that simulates rolling this die.
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*/
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int roll_weighted_die() {
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/*<< Add 1 to make sure that the result is in the range [1,6]
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instead of [0,5].
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>>*/
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return dist(gen) + 1;
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}
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//]
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#include <iostream>
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int main() {
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for(int i = 0; i < 10; ++i) {
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std::cout << roll_weighted_die() << std::endl;
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}
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}
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