【PAT】1017. Queueing at Bank

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考查点：模拟题

思路：用优先队列可提高效率，关键在于维护每个窗口的结束时间数组，每次遍历排队用户时更新结束时间，这里更新时多了个+号结果调了半天

#define LOCAL#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <cmath>#include <string>#include <vector>#include <map>#include <set>#include <queue>#include <stack>#define FOR(i, x, y) for(int i = x; i <= y; i++)#define rFOR(i, x, y) for(int i = x; i >= y; i--)#define MAXN 10010#define oo 0x3f3f3f3fusing namespace std;struct customer{    int start,process;}person[10010];bool cmp(customer a,customer b){    return a.start<b.start;}int wait[110];int main(){     #ifdef LOCAL        freopen("data.in","r",stdin);        freopen("data.out","w",stdout);    #endif // LOCAL    int n,k;     int hh,mm,ss,pp;    scanf("%d%d",&n,&k);    int num=0;    FOR(i,0,n-1)    {       scanf("%d:%d:%d %d",&hh,&mm,&ss,&pp);       int tmp=hh*3600+mm*60+ss;       if(tmp<=17*3600){            person[num].process=(pp<60?pp*60:3600);            person[num].start=tmp;            num++;       }    }    double sum=0;    sort(person,person+num,cmp);       FOR(i,0,k-1)    wait[i]=8*3600;    FOR(i,0,num-1)    {        int wmin=oo;int id;        FOR(j,0,k-1)        {            if(wait[j]<wmin){                wmin=wait[j];                id=j;            }        }        if(person[i].start<wait[id]){                sum+=(wait[id]-person[i].start);                wait[id]+=person[i].process;        }else{            wait[id]=(person[i].start+person[i].process);        }            }    if(num==0) printf("0.0");    else{    printf("%.1f",sum/60.0/num);    }    return 0;}

优先队列：由于默认最大值。所以要重载运算符

#define LOCAL#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <cmath>#include <string>#include <vector>#include <map>#include <set>#include <queue>#include <stack>#define FOR(i, x, y) for(int i = x; i <= y; i++)#define rFOR(i, x, y) for(int i = x; i >= y; i--)#define MAXN 10010#define oo 0x3f3f3f3fusing namespace std;struct customer{    int start,process;  bool operator<(const customer& a)const{        if(a.start<start)return true;        else return false;  }}person;struct window{    int time;    bool operator<(const window& a)const{        if(time>a.time)return true;        else return false;    }}w;bool cmp(customer a,customer b){    return a.start<b.start;}priority_queue<customer> cu;priority_queue<window> ww;int main(){     #ifdef LOCAL        freopen("data.in","r",stdin);        freopen("data.out","w",stdout);    #endif // LOCAL    int n,k;     int hh,mm,ss,pp;    scanf("%d%d",&n,&k);    int num=0;    FOR(i,0,n-1)    {       scanf("%d:%d:%d %d",&hh,&mm,&ss,&pp);       int tmp=hh*3600+mm*60+ss;       if(tmp<=17*3600){            person.process=(pp<60?pp*60:3600);            person.start=tmp;            cu.push(person);       }    }    double sum=0;    num=cu.size();    FOR(i,0,k-1)    {        w.time=8*3600;        ww.push(w);    }    while(!cu.empty())    {        w=ww.top();        int endt=w.time;        person=cu.top();        cu.pop();       if(endt<=person.start){            endt=person.start+person.process;            ww.pop();            w.time=endt;            ww.push(w);        }else{            sum+=(endt-person.start);            endt+=person.process;            ww.pop();            w.time=endt;            ww.push(w);        }    }    if(num==0) printf("0.0");    else{    printf("%.1f",sum/60.0/num);    }    return 0;}

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