// Copyright 2020 Xavier Gillard
//
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// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
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// subject to the following conditions:
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//! This module provides the implementation for some heuristics that may be used
//! to improve the behavior of the branch-and-bound-MDD solver for traveling
//! salesman problem with time windows.

use ddo::{StateRanking, WidthHeuristic, SubProblem};

use crate::state::TsptwState;

#[derive(Debug, Copy, Clone)]
pub struct TsptwRanking;

impl StateRanking for TsptwRanking {
    type State = TsptwState;

    fn compare(&self, sa: &Self::State, sb: &Self::State) -> std::cmp::Ordering {
        sa.depth.cmp(&sb.depth)
    }
}

pub struct TsptwWidth {
    nb_vars: usize,
    factor: usize,
}
impl TsptwWidth {
    pub fn new(nb_vars: usize, factor: usize) -> TsptwWidth {
        TsptwWidth { nb_vars, factor }
    }
}
impl WidthHeuristic<TsptwState> for TsptwWidth {
    fn max_width(&self, state: &SubProblem<TsptwState>) -> usize {
        self.nb_vars * (state.depth + 1) * self.factor
    }
}