【正经题解】外卖店优先级

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;

typedef pair<int, int> PII;  // 使用 PII 表示一个包含两个整数的 pair

const int N = 100010;

int n, m, T;
int priority[N], lastOrder[N];
bool inCache[N];
PII orders[N];

int main()
{
    scanf("%d%d%d", &n, &m, &T);  // 输入外卖店数量n、订单数量m、和时刻T

    for (int i = 0; i < m; i++)
        scanf("%d%d", &orders[i].first, &orders[i].second);  // 输入每个订单的时刻和外卖店编号

    sort(orders, orders + m);  // 按照时刻对订单进行排序

    for (int i = 0; i < m;)
    {
        int j = i;
        while (j < m && orders[j] == orders[i])
            j++;
        int time = orders[i].first, id = orders[i].second, count = j - i;
        i = j;

        // 处理 t 时刻之前的信息
        priority[id] -= time - lastOrder[id] - 1;
        if (priority[id] < 0)
            priority[id] = 0;
        if (priority[id] <= 3)
            inCache[id] = false;

        // 处理 t 时刻的信息
        priority[id] += count * 2;
        if (priority[id] > 5)
            inCache[id] = true;

        lastOrder[id] = time;
    }

    for (int i = 1; i <= n; i++)
        if (lastOrder[i] < T)
        {
            priority[i] -= T - lastOrder[i];
            if (priority[i] <= 3)
                inCache[i] = false;
        }

    int result = 0;
    for (int i = 1; i <= n; i++)
        result += inCache[i];

    printf("%d\n", result);  // 输出结果

    return 0;
}