A1095 Cars on Campus (30)

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思路：
1. 两次排序，第一次按照车牌号排序，然后标记该项纪录是否有效，并且更新最长停留时间
2. 第二次排序按照时间排序，然后根据查询一次遍历O(n)即可

#include<iostream>
#include<cstring>
#include<string>
#include<set>
#include<vector>
#include<algorithm>
using namespace std;
//1095 Cars on Campus (30)
//question：set<string>可以直接存放char数组
struct node{
    bool valied;
    char name[10],statue[4];
    string time;
    node():valied(false){}
};
bool cmpname(node& a,node& b){
    return strcmp(a.name,b.name)<0||(strcmp(a.name,b.name)==0&&a.time<b.time);
}
bool cmp(node& a,node& b){
    return a.time<b.time;
}
#define dd(a) (a-'0')
int countime(string& a,string& b){
    return (dd(b[0])*10+dd(b[1])-dd(a[0])*10-dd(a[1]))*3600+\
           (dd(b[3])*10+dd(b[4])-dd(a[3])*10-dd(a[4]))*60+\
           (dd(b[6])*10+dd(b[7])-dd(a[6])*10-dd(a[7]));
}
int main(){
    //freopen("D:\\input.txt","r",stdin);
    int N,K;
    scanf("%d %d",&N,&K);
    vector<node> lists(N);
    for(int i=0;i<N;i++){
        scanf("%s",lists[i].name);
        cin>>lists[i].time;
        scanf("%s",lists[i].statue);
    }
    //先标记各个节点的状态，即该记录是否有效
    sort(lists.begin(),lists.end(),cmpname);
    int lo=0,hi=1;
    int maxtime=0,tmptime=0;

    set<string> nameset;
    while(lo<N){
        tmptime=0;
        while(hi<N&&strcmp(lists[lo].name,lists[hi].name)==0)hi++;
        for(int i=lo;i<hi-1;i++){
            if(lists[i].statue[0]=='i'&&lists[i+1].statue[0]=='o'){
                lists[i].valied=true;lists[i+1].valied=true;
                //cout<<lists[i].time<<" "<<lists[i+1].time<<endl;
                tmptime+=countime(lists[i].time,lists[i+1].time);
                i++;
            }
        }
        if(tmptime>maxtime){
            maxtime=tmptime;
            nameset.clear();
            nameset.insert(lists[lo].name);
        }else if(tmptime==maxtime){
            nameset.insert(lists[lo].name);
        }
        lo=hi;hi=lo+1;
    }
    //查询车辆数
    sort(lists.begin(),lists.end(),cmp);
    int r=0;//记录车辆信息的位置
    int count=0;//学校内的车辆数
    string time;
    for(int i=0;i<K;i++){
        cin>>time;
        while(r<N&&lists[r].time<=time){
            if(lists[r].valied){
                if(lists[r].statue[0]=='i')count++;
                else count--;
            }
            r++;
        }
        printf("%d\n",count);
    }

    set<string>::iterator it=nameset.begin();
    cout<<(*it);
    //printf("%s",it->c_str);
    it++;
    while(it!=nameset.end()){
        cout<<" "<<*it;
        it++;
    }
    int ss=maxtime%60,mm=maxtime/60%60,hh=maxtime/3600;
    printf(" %02d:%02d:%02d\n",hh,mm,ss);

    return 0;
}

/*这种写法也是可以的
    set<string>nameset;
    char name[10];
    for(int i=0;i<5;i++){
        scanf("%s",name);
        nameset.insert(name);
    }
*/