1095 Cars on Campus

题目：Cars on Campus

思路：两次排序：第一次通过车牌排序，然后判断数据是否合法，并找出最长的停车时间；第二次通过时间排序，按时间统计出车辆数。

代码：

#include<cstdio>
#include<string>
#include<vector>
#include<iostream>
#include<algorithm>
#include<map>
using namespace std;
class CAR{
    public:
        string Pnum;
        int time;
        int status;
        bool isValid;
        CAR(string num1,int time1,int status1){
            Pnum = num1;
            time = time1;
            status = status1;
            isValid = false;
        }
};

int main(){
    int N, K;
    scanf("%d %d", &N, &K);
    vector<CAR> parking;
    string t_pnum;
    int t_hour, t_min, t_sec;
    string t_status;
    for (int i = 0; i < N;i++){
        cin >> t_pnum;
        scanf("%d:%d:%d", &t_hour, &t_min, &t_sec);
        int tempt = t_hour * 3600 + t_min * 60 + t_sec;
        cin >> t_status;
        int temps = t_status[0] == 'i' ? 0 : 1;
        parking.emplace_back(t_pnum, tempt, temps);
    }
    sort(parking.begin(), parking.end(), [](CAR x, CAR y){
        if(x.Pnum.compare(y.Pnum)==0){
            return x.time < y.time;
        }else{
            return x.Pnum.compare(y.Pnum)<0;
        }
    });
    int maxlength = 0;
    map<string, int> lenth;
    vector<string> longest;
    for (int i = 0; i+1 < parking.size();++i){
        if(parking[i].status == 0){
            if(parking[i+1].status == 1 && parking[i].Pnum.compare(parking[i+1].Pnum) == 0){
                auto it = lenth.find(parking[i].Pnum);
                if(it!=lenth.end())
                {
                    it->second += (parking[i + 1].time - parking[i].time);
                }else{
                    lenth[parking[i].Pnum] = (parking[i + 1].time - parking[i].time);
                }
                if(lenth[parking[i].Pnum] > maxlength){
                    maxlength = lenth[parking[i].Pnum];
                }
                parking[i].isValid = parking[i + 1].isValid = true;
            }
        }
    }
    for (auto it = lenth.begin(); it != lenth.end();++it){
        if(it->second == maxlength){
            longest.push_back(it->first);
        }
    }
    sort(longest.begin(), longest.end(), [](string x, string y) {
        return x.compare(y) < 0;
    });
    sort(parking.begin(), parking.end(), [](CAR x, CAR y) {
        if(x.time == y.time){
            return x.Pnum.compare(y.Pnum) < 0;
        }else{
            return x.time < y.time;
        }
    });
    int j = 0;
    int numCar = 0;
    for (int i = 0; i < K;i++){
        int hh, mm, ss;
        scanf("%d:%d:%d", &hh, &mm, &ss);
        int temp = hh * 3600 + mm * 60 + ss;
        for (; j<parking.size() && temp >= parking[j].time;j++){
            if(parking[j].isValid){
                if(parking[j].status == 0){
                    numCar++;
                }else{
                    numCar--;
                }
            }
        }
        cout << numCar << endl;
    }

    // for (auto it = parking.begin(); it != parking.end();it++){
    //     cout << it->Pnum << " " << it->status << " " << it->time << " " << it->isValid<<endl;
    // }
     for (auto it = longest.begin(); it != longest.end();it++){
         cout << *it << " ";
     }
     int hh, mm, ss;
     hh = maxlength / 3600;
     maxlength %= 3600;
     mm = maxlength / 60;
     maxlength %= 60;
     ss = maxlength;
     printf("%02d:%02d:%02d", hh, mm, ss);
     return 0;
}

C++语法复习

• vector
  • emplace_back() 添加，需要构造函数
• map
  • find() 找不到返回 .end()
  • map迭代器 it->first是key，it->second是value
• lambda