Hint HolmesBot::bestHintForPlayer()

in csrc/HolmesBot.cc [500:571]

• 62 lines of code
• 25 McCabe index (conditional complexity)

Hint HolmesBot::bestHintForPlayer(const Server &server, int partner) const
{
    assert(partner != me_);
    const std::vector<Card> partners_hand = server.handOfPlayer(partner);

    bool is_really_playable[5];
    for (int c=0; c < partners_hand.size(); ++c) {
        is_really_playable[c] =
            server.pileOf(partners_hand[c].color).nextValueIs(partners_hand[c].value);
    }

    Hint best_so_far;
    best_so_far.to = partner;

    /* Can we construct a color hint that gives our partner information
     * about unknown-playable cards, without also including any
     * unplayable cards? */
    for (Color color = RED; color <= BLUE; ++color) {
        int information_content = 0;
        bool misinformative = false;
        for (int c=0; c < partners_hand.size(); ++c) {
            const CardKnowledge &knol = handKnowledge_[partner][c];
            if (partners_hand[c].color != color) continue;
            if (is_really_playable[c] && !knol.isPlayable) {
                information_content += 1;
            } else if (!is_really_playable[c] && (knol.value() == -1 && !knol.isWorthless)) {
                misinformative = true;
                break;
            }
        }
        if (misinformative) continue;
        if (information_content > best_so_far.information_content) {
            best_so_far.information_content = information_content;
            best_so_far.color = color;
            best_so_far.value = -1;
        }
    }

    /* Avoid giving hints that could be misinterpreted as warnings. */
    const int discardIndex = nextDiscardIndex(server, partner);
    int valueToAvoid = -1;
    if (discardIndex != -1) {
        const CardKnowledge &knol = handKnowledge_[partner][discardIndex];
        valueToAvoid = partners_hand[discardIndex].value;
        if (!couldBeValuable(server, knol, valueToAvoid)) valueToAvoid = -1;
    }

    for (int value = 1; value <= 5; ++value) {
        if (value == valueToAvoid) continue;
        int information_content = 0;
        bool misinformative = false;
        for (int c=0; c < partners_hand.size(); ++c) {
            const CardKnowledge &knol = handKnowledge_[partner][c];
            if (partners_hand[c].value != value) continue;
            if (is_really_playable[c] && !knol.isPlayable)
            {
                information_content += 1;
            } else if (!is_really_playable[c] && (knol.color() == -1 && !knol.isWorthless)) {
                misinformative = true;
                break;
            }
        }
        if (misinformative) continue;
        if (information_content > best_so_far.information_content) {
            best_so_far.information_content = information_content;
            best_so_far.color = -1;
            best_so_far.value = value;
        }
    }

    return best_so_far;
}