1095. Cars on Campus (30)

    考查结构体排序，需要足够细心，大致思路是先将所有记录按车牌号排序，车牌号一样按时间排序，然后将合法的记录挑选出来。在查询的时候，维护当前已经查询到何处，下一次查询从当前位置开始。查询中，如果是进的，则把当前车辆数加1，出的则减1，同时更新车辆所停靠的时间，顺便选出最长停靠时间及相关车辆。

#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <cstring>
#include <functional>
#include <unordered_map>

using namespace std;

struct Record{
char plate[10];
int time;
int period;
char status;

bool in(){
return status == 'i';
}

bool out(){
return status == 'o';
}

Record(char p[], int t, char s) : time(t), period(0), status(s){
strcpy(plate, p);
}
};

bool cmpPlate(const Record& lhs, const Record& rhs){
return strcmp(lhs.plate, rhs.plate) < 0
|| (strcmp(lhs.plate, rhs.plate) == 0 && lhs.time < rhs.time);
}

bool cmpTime(const Record& lhs, const Record& rhs){
return lhs.time < rhs.time;
}

int tosec(int hh, int mm, int ss){
return hh*3600 + mm*60 + ss;
}

int main(){
int n, k, hh, mm, ss;
scanf("%d%d", &n, &k);

vector<Record> inputs;
for(int i = 0; i < n; ++i){
char plate[10], status[10];

scanf("%s %d:%d:%d %s", plate, &hh, &mm, &ss, status);
inputs.emplace_back(plate, tosec(hh, mm, ss), status[0]);
}

sort(begin(inputs), end(inputs), cmpPlate);

vector<Record> records;
for(int i = 0; i+1 < (int)inputs.size(); i += 2){
if(strcmp(inputs[i].plate, inputs[i+1].plate) == 0
&& inputs[i].in() && inputs[i+1].out()){

inputs[i].period = inputs[i+1].time - inputs[i].time;
inputs[i+1].period = inputs[i+1].time - inputs[i].time;
records.push_back(inputs[i]);
records.push_back(inputs[i+1]);
}else{
--i;
}
}

sort(begin(records), end(records), cmpTime);

int idx = 0, sum = 0, maxTime = -1;
vector<Record> result;
unordered_map<string, int> times;

auto query = [&](int t){
for(; idx < (int)records.size(); ++idx){
if(records[idx].time > t) break;
if(records[idx].in()){
++sum;
}else{
--sum;

string plate = records[idx].plate;
if(times.find(plate) == times.end()){
times.insert({plate, 0});
}

times[plate] += records[idx].period;

if(times[plate] > maxTime){
maxTime = times[plate];
result = vector<Record>(1, records[idx]);
}else if(times[plate] == maxTime){
result.push_back(records[idx]);
}
}
}
};

for(int i = 0; i < k; ++i){
scanf("%d:%d:%d", &hh, &mm, &ss);
int t = hh*3600 + mm*60 + ss;

query(t);
printf("%d\n", sum);
}

query(24*3600);

sort(begin(result), end(result), cmpPlate);
for(auto& r : result){
printf("%s ", r.plate);
}

hh = maxTime/3600; maxTime %= 3600;
mm = maxTime/60; maxTime %= 60;
ss = maxTime;

printf("%02d:%02d:%02d", hh, mm, ss);

return 0;
}