vdiff_tiebreaker_impl.h

#include "probfd/policy_pickers/vdiff_tiebreaker.h"
 
#include "probfd/algorithms/state_properties.h"
 
#include "probfd/interval.h"
 
namespace probfd::policy_pickers {
 
template <typename State, typename Action>
VDiffTiebreaker<State, Action>::VDiffTiebreaker(
    bool stable_policy,
    value_t favor_large_gaps)
    : VDiffTiebreaker::StablePolicyPicker(stable_policy)
    , favor_large_gaps_(favor_large_gaps)
{
}
 
template <typename State, typename Action>
int VDiffTiebreaker<State, Action>::pick_index(
    MDP<State, Action>&,
    std::optional<Action>,
    const std::vector<Transition<Action>>& greedy_transitions,
    algorithms::StateProperties& properties)
{
    auto it = std::ranges::min_element(
        greedy_transitions,
        [](value_t lhs, value_t rhs) { return is_approx_less(lhs, rhs); },
        [&properties, factor = favor_large_gaps_](const Transition<Action>& t) {
            return t.successor_dist.expectation([&](StateID id) {
                return factor * properties.lookup_bounds(id).length();
            });
        });
 
    return std::distance(greedy_transitions.begin(), it);
}
 
} // namespace probfd::policy_pickers