Uva - 1598 - Exchange

本来想用优先队列做，可是不知道怎么处理之间的关系，最后还是用了map方法AC了，不过速度上有些慢，提交的时候跑了1.557秒。估计这道题时间都稍微长些，题目的时间限制也是4.5秒，不像一般题目的3秒限制。

AC代码：

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cstring>
#include <string>
#include <sstream>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <stack>
#include <queue>
#include <bitset>
#include <cassert> 

using namespace std;

struct CMD {
	string cmd;
	int size, price;
	CMD(string kind, int x = 0, int y = 0) :cmd(kind), size(x), price(y) {}
};

map<int, set<int> > BUY, SELL;
map<int, int> BUY_VAL, SELL_VAL;
vector<CMD> D;

void trade(int kind)
{
	while (!BUY.empty() && !SELL.empty()) {
		if (BUY.rbegin()->first >= SELL.begin()->first) {
			set<int> &v1 = BUY.rbegin()->second;
			set<int> &v2 = SELL.begin()->second;
			int aid = *v1.begin(), bid = *v2.begin();
			int z = min(D[aid].size, D[bid].size);
			printf("TRADE %d %d\n", z, kind ? D[aid].price : D[bid].price);
			D[aid].size -= z, D[bid].size -= z;
			BUY_VAL[D[aid].price] -= z, SELL_VAL[D[bid].price] -= z;
			if (D[aid].size == 0)
				v1.erase(aid);
			if (D[bid].size == 0)
				v2.erase(bid);
			if (v1.size() == 0)
				BUY.erase(D[aid].price);
			if (v2.size() == 0)
				SELL.erase(D[bid].price);
		}
		else {
			return;
		}
	}
}

// 打印QUOTE一行
void print()
{
	while (BUY_VAL.size() && BUY_VAL.rbegin()->second == 0) {
		BUY_VAL.erase(BUY_VAL.rbegin()->first);
	}
	while (SELL_VAL.size() && SELL_VAL.begin()->second == 0) {
		SELL_VAL.erase(SELL_VAL.begin()->first);
	}
	printf("QUOTE ");
	if (BUY_VAL.size()) {
		printf("%d %d", BUY_VAL.rbegin()->second, BUY_VAL.rbegin()->first);
	}
	else {
		printf("0 0");
	}
	printf(" - ");
	if (SELL_VAL.size()) {
		printf("%d %d", SELL_VAL.begin()->second, SELL_VAL.begin()->first);
	}
	else {
		printf("0 99999");
	}
	cout << endl;
}

int main()
{
	int Q, cases = 0;
	char cmd[16];
	while (scanf("%d", &Q) == 1) {
		if (cases++)
		{
			cout << endl;
		}
		// 记得清空
		BUY.clear(), SELL.clear();
		BUY_VAL.clear(), SELL_VAL.clear();
		D.clear();
		int size, price, id;
		// 读入命令并处理交易
		for (int i = 0; i < Q; i++) {
			scanf("%s", cmd);
			if (!strcmp(cmd, "BUY")) {
				scanf("%d %d", &size, &price);
				BUY[price].insert(i);
				BUY_VAL[price] += size;
				D.push_back(CMD("BUY", size, price));
				trade(0);
			}
			else if (!strcmp(cmd, "SELL")) {
				scanf("%d %d", &size, &price);
				SELL[price].insert(i);
				SELL_VAL[price] += size;
				D.push_back(CMD("SELL", size, price));
				trade(1);
			}
			else if (!strcmp(cmd, "CANCEL")) {
				scanf("%d", &id), id--;
				D.push_back(CMD("CANCEL", id));
				if (D[id].cmd == "BUY") {
					BUY[D[id].price].erase(id);
					if (BUY[D[id].price].size() == 0)
						BUY.erase(D[id].price);
					BUY_VAL[D[id].price] -= D[id].size;
					D[id].size = 0;
				}
				if (D[id].cmd == "SELL") {
					SELL[D[id].price].erase(id);
					if (SELL[D[id].price].size() == 0)
						SELL.erase(D[id].price);
					SELL_VAL[D[id].price] -= D[id].size;
					D[id].size = 0;
				}
			}
			print();
		}
	}
	return 0;
}