crateMover9001.cc

struct Order {
    uint32_t count;
    size_t from;
    size_t to;
};

void crateMover9001(std::vector<std::vector<char>>& state, 
                    const std::vector<Order>& orders) {
    for (auto &order : orders) {
        // view of the last order.count elements in order
        auto src = state[order.from] | 
          std::views::reverse | std::views::take(order.count) |
          std::views::reverse;
        std::ranges::copy(src, std::back_inserter(state[order.to]));
        // remove the last order.count elements
        state[order.from].resize(state[order.from].size()-order.count);
    }
}

std::string top_crates(const std::vector<std::vector<char>>& state) {
    std::string result;
    for (auto &stack : state) {
        if (stack.size() == 0) continue;
        result += stack.back();
    }
    return result;
}