everybodycodes S2 Q1 Part 3

pair<int,int> part3(const vector<string>& grid, const vector<string>& sequence) {
    constexpr int INF = 1e9;
    const int n = (int)grid[0].size(), slots = (n + 1) / 2, tokens = (int)sequence.size(), m = 1 << tokens;
    vector winnings(slots, vector<int>(tokens));
    for (int slot = 0; slot < slots; slot++) {
        for (int token = 0; token < tokens; token++)
            winnings[slot][token] = max(0, runSlot(grid, n, slot * 2, sequence[token]) * 2 - slot - 1);
    }
    vector dp_min(m, INF), dp_max(m, 0);
    dp_min[0] = 0;
    for (int slot = 0; slot < slots; slot++) {
        for (int mask = m - 1; mask > 0; mask--) {
            int mask1 = mask;
            while (mask1) {
                const int token = __builtin_ctz(mask1);
                dp_min[mask] = min(dp_min[mask], dp_min[mask - (1 << token)] + winnings[slot][token]);
                dp_max[mask] = max(dp_max[mask], dp_max[mask - (1 << token)] + winnings[slot][token]);
                mask1 -= 1 << token;
            }
        }
    }
    return {dp_min.back(),dp_max.back()};
}