暴力 C++

一个面试题。主要复习C++语法与STL和list sort 二元谓语函数编写。

#include<stdio.h>
#include<string.h>
#include<vector>
#include<algorithm>
#include<iostream>
#include<list>

using namespace std;

/*
    authhor: ramanu_jan
*/

/**
*   the Order class
*/
class Order{
    public:
         Order(){}
         Order(string order_type, int price, int quantity, string order_id){
            this->order_type = order_type;  this->price = price;
            this->quantity = quantity;      this->order_id = order_id;
         }
         int get_price(){return price;}
         int get_quantity(){return quantity;}
         string get_order_id(){return order_id;}
         string get_order_type(){return order_type;}
         void set_price(int price){this->price = price;}
         void set_quantity(int quantity){this->quantity = quantity;}
         void set_order_id(string order_id){this->order_id = order_id;}
    private:
        string order_id;
        string order_type;
        int price;
        int quantity;
};

/**
*   use a buy list and a sell list to save orders for potential trades and PRINT operation.
*   some string constants
*/
list<Order> l_buy, l_sell;
const string BUY("BUY"), SELL("SELL"), CANCEL("CANCEL"),
             IOC("IOC"), GFD("GFD"), MODIFY("MODIFY"), PRINT("PRINT");

// buy operation
void buy(Order order){
    list<Order>::iterator itr;
    //check if IOC orders exists, and cancel it when exist.
    for(itr = l_buy.begin(); itr != l_buy.end(); itr++)
        if(itr->get_order_type() == IOC) l_buy.erase(itr);
    //check the trade condition if exists, conducts the trade when exists.
    for(itr = l_sell.begin(); itr != l_sell.end(); itr++){
        if(order.get_price() >= itr->get_price()){      // trade occurs
            int traded_quantity = min(itr->get_quantity(), order.get_quantity());
            cout << "TRADE " << itr->get_order_id() << " " << itr->get_price() << " " << traded_quantity << " "
                             << order.get_order_id() << " " << order.get_price() << " " << traded_quantity << endl;
            if(order.get_quantity() >= itr->get_quantity()){
                order.set_quantity(order.get_quantity() - itr->get_quantity());
                l_sell.erase(itr);
            }
            else{
                itr->set_quantity(itr->get_quantity() - order.get_quantity());
                order.set_quantity(0);  break;
            }
        }
    }
    //check if there is IOC type orders in sell queue, cancel them when there's.
    for(itr = l_sell.begin(); itr !=l_sell.end(); itr++)
        if(itr->get_order_type() == IOC) l_sell.erase(itr);

    if(order.get_quantity() > 0) l_buy.push_back(order);
}

// sell operation
void sell(Order order){
    list<Order>::iterator itr;
    //check if IOC orders exists, and cancel it when exist.
    for(itr = l_sell.begin(); itr != l_sell.end(); itr++)
        if(itr->get_order_type() == IOC) l_sell.erase(itr);
    //check the trade condition if exists, conducts the trade when exists.
    for(itr = l_buy.begin(); itr !=l_buy.end(); itr++){
        if(itr->get_price() >= order.get_price()){
            int traded_quantity = min(itr->get_quantity(), order.get_quantity());
            cout << "TRADE " << itr->get_order_id() << " " << itr->get_price() << " " << traded_quantity << " "
                             << order.get_order_id() << " " << order.get_price() << " " << traded_quantity << endl;
            if(order.get_quantity() >= itr->get_quantity()){
                order.set_quantity(order.get_quantity() - itr->get_quantity());
                l_buy.erase(itr);
            }
            else{
                itr->set_quantity(itr->get_quantity() - order.get_quantity());
                order.set_quantity(0);  break;
            }
        }
    }
    //check if there is IOC type orders in buy queue, cancel them when there's.
    for(itr = l_buy.begin(); itr != l_buy.end(); itr++)
        if(itr->get_order_type() == IOC) l_buy.erase(itr);
    if(order.get_quantity() > 0) l_sell.push_back(order);
}

// sell operation: check the input order id if exists in list sell and buy, cancel that when exists.
void cancel(string order_id){
    list<Order>::iterator itr;
    for(itr = l_buy.begin(); itr != l_buy.end(); itr++)
        if(order_id == itr->get_order_id()){
            l_buy.erase(itr);   break;
        }
    for(itr = l_sell.begin(); itr != l_sell.end(); itr++)
        if(order_id == itr->get_order_id()){
            l_sell.erase(itr);  break;
        }
}

//modify operation
void modify(string order_id, string todo, int price, int quantity){
    list<Order>::iterator itr;
    //check if IOC orders exists, cancel them if exists.
    for(itr = l_sell.begin(); itr != l_sell.end(); itr++) if(itr->get_order_type() == IOC)
        l_sell.erase(itr);
    for(itr = l_buy.begin(); itr != l_buy.end(); itr++) if(itr->get_order_type() == IOC)
        l_buy.erase(itr);

    //check sell orders
    for(itr = l_sell.begin(); itr != l_sell.end(); itr++) if(itr->get_order_id() == order_id){
        //when nothing modified, we just do nothing
        //in other cases, we shall check if there is a trade.
        if(todo == SELL && price == itr->get_price() && quantity == itr->get_quantity()) return;
        Order order(itr->get_order_type(), price, quantity, order_id);
        l_sell.erase(itr);
        if(todo == SELL) sell(order);
        else buy(order);
        return;
    }

    //check buy orders
    for(itr = l_buy.begin(); itr != l_sell.end(); itr++) if(itr->get_order_id() == order_id){
       if(todo == BUY && price == itr->get_price() && quantity == itr->get_quantity()) return;
        Order order(itr->get_order_type(), price, quantity, order_id);
        l_buy.erase(itr);
        if(todo == BUY) buy(order);
        else sell(order);
        return;
    }
}

bool cmp(Order x, Order y){
    return x.get_price() > y.get_price();
}

/**
*   use backup lists to sort and integrate orders by price and different lists they are in, then print them out.
*/
void print(){
    list<Order> lbuy(l_buy), lsell(l_sell);
    lbuy.sort(cmp);        lsell.sort(cmp);
    if(lbuy.size() > 1){
        list<Order>::iterator pre = lbuy.begin(), cur = pre;    cur++;
        while(cur != lbuy.end()){
            if(cur->get_price() == pre->get_price()){
                cur->set_quantity(cur->get_quantity() + pre->get_quantity());
                lbuy.erase(pre);
                pre = cur;
            }
            cur++;
        }
    }

    if(lsell.size() > 1){
        list<Order>::iterator pre = lsell.begin(), cur = pre;   cur++;
        while(cur != lsell.end()){
            if(cur->get_price() == pre->get_price()){
                cur->set_quantity(cur->get_quantity() + pre->get_quantity());
                lsell.erase(pre);
                pre = cur;
            }
            cur++;
        }
    }

    list<Order>::iterator itr;
    cout << "SELL:" << endl;
    for(itr = lsell.begin(); itr != lsell.end(); itr++)
        cout << itr->get_price() << " " << itr->get_quantity() << endl;
    cout << "BUY:" << endl;
    for(itr = lbuy.begin(); itr != lbuy.end(); itr++)
        cout << itr->get_price() << " " << itr->get_quantity() << endl;
}

int main(){
    l_buy.clear();    l_sell.clear();
    string str;
    while(cin >> str){
        if(str == BUY){
            string order_type, order_id;  int price, quantity;
            cin >> order_type >> price >> quantity >> order_id;
            Order order(order_type, price, quantity, order_id);
            buy(order);
        }
        else if(str == SELL){
            string order_type, order_id;  int price, quantity;
            cin >> order_type >> price >> quantity >> order_id;
            Order order(order_type, price, quantity, order_id);
            sell(order);
        }
        else if(str == CANCEL){
            string order_id;
            cin >> order_id;
            cancel(order_id);
        }
        else if(str == MODIFY){
            string order_id, todo;  int quantity, price;
            cin >> order_id >> todo >> price >> quantity;
            modify(order_id,todo, price, quantity);
        }
        else print();
    }
    return 0;
}