To Fill or Not to Fill（贪心模拟）

  1 #include<stdio.h>
  2 #include<algorithm>
  3 #include<iostream>
  4 #include<cstring>
  5 using namespace std;
  6  
  7 typedef struct{
  8     double pri;
  9     int dis;
 10 }Station;
 11  
 12 bool cmp(const Station &A, const Station &B){
 13     if(A.dis!=B.dis)
 14         return A.dis<B.dis;
 15     else
 16         return A.pri<B.pri;
 17 }
 18 int Cmax, D, Davg, tmp1;
 19 int N, i, j, tmp_ind;
 20 double tank, now_pos, now_pri, tot_cost, comp, tmp_pos;
 21 bool flag, flag2, flag3, flag4;
 22 Station S[550];
 23 int main(){
 24     while(~scanf("%d%d%d%d",&Cmax,&D,&Davg,&N)){
 25         memset(S,0,sizeof(S));
 26         tank=0;
 27         now_pos=0;
 28         tot_cost=0;
 29         for(i=0;i<N;i++)
 30             scanf("%lf%d",&S[i].pri,&S[i].dis);
 31         sort(S,S+N,cmp);
 32         S[N].dis=D;
 33         S[N].pri=0;
 34         if(S[0].dis!=0||N==0){
 35             printf("The maximum travel distance = 0.00\n");
 36             continue;
 37         }
 38         for(i=0;i<N;i++){
 39             flag=false;
 40             flag2=false;
 41             flag3=false;
 42             flag4=false;
 43             if(i+1<N){
 44                 comp=S[i+1].pri;
 45                 tmp_pos=S[i+1].dis;
 46             }
 47             for(j=i+1;j<=N;j++){
 48                 if(S[j].dis<=now_pos+Cmax*Davg&&S[j].dis>=now_pos){
 49                     flag=true;
 50                     if(S[j].pri<S[i].pri){
 51                         if(S[j].dis<=now_pos+tank*Davg){
 52                             //价格比较低，现有的油可以开到那里
 53                             tank-=(S[j].dis-now_pos)/Davg;
 54                             now_pos=S[j].dis;
 55                         }
 56                         else{
 57                             //价格比较低，到那里再加油
 58                             tot_cost+=S[i].pri*((S[j].dis-now_pos)/Davg-tank);
 59                             tank=0;
 60                             now_pos=S[j].dis;
 61                         }
 62                         i=j-1;
 63                         flag2=true;
 64                         break;
 65                     }
 66                     else{
 67                         flag4=true;
 68                         if(S[j].pri<=comp){
 69                             comp=S[j].pri;
 70                             tmp_pos=S[j].dis;
 71                             tmp_ind=j;
 72                         }
 73                     }
 74                 }
 75             }
 76             if(flag2)
 77                 continue;
 78             if(now_pos+Cmax*Davg>=tmp_pos){
 79                 //可开到的加油站中价格相对较低，在本地加满油，开到该加油站
 80                 tot_cost+=(double)(Cmax-tank)*S[i].pri;
 81                 tank=(double)(Cmax-(double)(tmp_pos-now_pos)/Davg);
 82                 now_pos=tmp_pos;
 83             }
 84             else{
 85                 //开不到该加油站
 86                 now_pos+=Cmax*Davg;
 87                 tot_cost+=(double)(Cmax-tank)*S[i].pri;
 88                 printf("The maximum travel distance = %.2lf\n",now_pos);
 89                 flag3=true;
 90                 break;
 91             }
 92             if(flag4)
 93                 i=tmp_ind-1;
 94             if(!flag&&now_pos<(double)D){
 95                 printf("The maximum travel distance = %.2lf\n",now_pos+tank*Davg);
 96                 flag3=true;
 97                 break;
 98             }
 99         }
100         if(!flag3)
101             printf("%.2lf\n",tot_cost);
102     }
103 }
104  
105 /**************************************************************
106     Problem: 1437
107     User: blueprintf
108     Language: C++
109     Result: Accepted
110     Time:10 ms
111     Memory:1532 kb
112 ****************************************************************/