202104 CSP认证 | DHCP服务器

3. DHCP服务器

在这里插入图片描述

我天呢经历了带配额的文件系统我真的极其挫败，然后开始写的时候觉得这个题感觉怎么有点简单…然后就觉得肯定是自己有很多东西没有想到，而且写的时候破罐子破摔觉得肯定会超时…
结果一写！哦买噶居然满分了！
脑子不清醒的时候写的差不多也就两个小时不到吧，天哪第三题要是是这种难度也太幸福了orz

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1e5 +10;
string H;
ll M, Tdef, Tmax, Tmin;
map<string, set<ll> > user_ip;struct Ip{   //定义一个IP结构体int status = 1; //1表示未分配,2表示待分配,3表示占用,4表示过期string user = "";ll ddl = 0;
};
Ip ipPool[N];  //定义一个IP池bool compare(string a, string b)
{if(a.size() != b.size()) return false;for(int i = 0;i < a.size();i ++){if(a[i] != b[i])return false;}return true;
}
//在每个时刻前进行检查
void check(ll t)
{for(ll i = 1;i <= M;i ++){if(ipPool[i].ddl && t >= ipPool[i].ddl){if(ipPool[i].status == 2){   //待分配状态ipPool[i].status = 1;string user = ipPool[i].user;ipPool[i].user = "";ipPool[i].ddl = 0;user_ip[user].erase(i);if(!user_ip[user].size())user_ip.erase(user);}else if(ipPool[i].status == 3){  //占用变为过期ipPool[i].status = 4;ipPool[i].ddl = 0;}}}
}
void Discover(const ll t,const string from,const string to,const ll ddl)
{ll id; bool flag = false;if(to != "*")  return;if(user_ip.count(from)){id = *user_ip[from].begin();  //取出第一个flag = true;}else {for(ll i = 1;i <= M ;i ++){if(ipPool[i].status == 1){id = i;flag = true;break;}}for(ll i = 1;i <= M && !flag;i ++){if(ipPool[i].status == 4){id = i;string user = ipPool[i].user;user_ip[user].erase(i);if(!user_ip[user].size()) user_ip.erase(user);flag = true;break;}}}if(!flag) return;ipPool[id].status = 2;ipPool[id].user = from;user_ip[from].insert(id);ll overtime;if(!ddl) overtime = t + Tdef;else{if(ddl - t >= Tmin && ddl - t <= Tmax) overtime = ddl;else if(ddl - t > Tmax) overtime = t + Tmax;else overtime = t + Tmin;}ipPool[id].ddl = overtime;cout << H <<' '<<from<<' '<<"OFR "<<id<<' '<<overtime<<"\n";
}void Request(const ll t,const string from,const string to,const ll ip,const ll ddl)
{if(to == "*") return;if(!compare(to, H)){auto temp = user_ip[from];for(auto x : temp){if(ipPool[x].status == 2){ipPool[x].status = 1;ipPool[x].user = "";ipPool[x].ddl = 0;user_ip[from].erase(x);}}if(!user_ip[from].size()) user_ip.erase(from);return;}if(ip >= 1 && ip <= M && compare(ipPool[ip].user, from)){ipPool[ip].status = 3;ll overtime;if(!ddl) overtime = t + Tdef;else{if(ddl - t >= Tmin && ddl - t <= Tmax) overtime = ddl;else if(ddl - t > Tmax) overtime = t + Tmax;else overtime = t + Tmin;}ipPool[ip].ddl = overtime;cout << H <<' '<<from<<' '<<"ACK "<<ip<<' '<<overtime<<"\n";}else{  //发送Nak报文cout << H <<' '<<from<<' '<<"NAK "<<ip<<' '<<0<<"\n";}
}
int main()
{ll n;cin >> M >> Tdef >> Tmax >> Tmin >> H;cin >> n;for(ll i = 1;i <= M;i ++){ipPool[i].status = 1;ipPool[i].ddl = 0;ipPool[i].user = "";}while(n --){ll t, ip ,ddl;string from, to , type;cin >> t >> from >> to >> type >> ip >> ddl;check(t);if(type == "DIS"){Discover(t,from,to,ddl);}else if(type == "REQ"){Request(t, from, to, ip, ddl);}}return 0;
}