二维数组+排序

一定注意判断顺序
详细的看这个

https://www.acwing.com/solution/content/40716/

C++ 代码

#include <bits/stdc++.h>
using namespace std;
int n, m, t, x, y;
vector<int> va;
bool is[100005];
int main()
{
    ios ::sync_with_stdio(false);
    cin.tie(0);
    cin >> n >> m >> t;
    vector<int> vec[n + 1];
    for (int i = 0; i < m; i++)
    {
        cin >> x >> y;
        vec[y].push_back(x);
    }

    for (int i = 1; i < n + 1; i++)
    {
        if (vec[i].size() == 0)
            continue;
        int s = t - *max_element(vec[i].begin(), vec[i].end());
        sort(vec[i].begin(), vec[i].end());
        int ct = 2;
        for (int j = 1; j < vec[i].size(); j++)
        {
            if (vec[i][j] - vec[i][j - 1] <= 1)
            {
                if (ct <= 3)
                    is[i] = 0;
                ct += 2;
                if (ct > 5)
                {
                    is[i] = 1;
                }
                continue;
            }
            ct = ct - (vec[i][j] - vec[i][j - 1] - 1);
            if (ct <= 3)
                is[i] = 0;
            if (ct < 0)
            {
                ct = 0;
                is[i] = 0;
            }
            ct += 2;
            if (ct > 5)
            {
                is[i] = 1;
            }
        }
        if (is[i] || ct > 5)
        {
            if ((ct - s) > 3)
                va.push_back(i);
        }
    }
    cout << va.size();
    return 0;
}