PAT 1033

  1 import java.util.*;
  2 import java.io.*;
  3 
  4 class FastReader{
  5     BufferedReader reader;
  6     StringTokenizer tokenizer;
  7     
  8     public FastReader(InputStream stream){
  9         reader = new BufferedReader(new InputStreamReader(stream), 1 << 22);
 10         tokenizer = null;
 11     }
 12     
 13     public String next(){
 14         while (tokenizer == null || !tokenizer.hasMoreTokens()){
 15             try { 
 16                 tokenizer = new StringTokenizer(reader.readLine());
 17             } catch (Exception e){
 18                 //System.out.println(-1);
 19                 throw new RuntimeException(e);
 20             }
 21         }
 22         
 23         return tokenizer.nextToken();
 24     }
 25     
 26     public int next_int(){
 27         return Integer.parseInt(next());
 28     }
 29     
 30     public float next_float(){
 31         return Float.parseFloat(next());
 32     }
 33 }
 34 
 35 class StationInfo{
 36     float dist;
 37     float price;
 38 }
 39 
 40 public class Main {
 41     public static void main(String[] args){
 42         FastReader reader = new FastReader(System.in);
 43         float cap, dist, avg_dist;
 44         int num;
 45         
 46         cap = reader.next_float();
 47         dist = reader.next_float();
 48         avg_dist = reader.next_float();
 49         num = reader.next_int();
 50         
 51         float longest_run = avg_dist * cap;
 52         StationInfo[] stations = new StationInfo[num + 1];
 53         for (int i = 0; i < num; i++){
 54             stations[i] = new StationInfo();
 55             stations[i].price = reader.next_float();
 56             stations[i].dist = reader.next_int();
 57         }
 58         stations[num] = new StationInfo();
 59         stations[num].dist = dist;
 60         stations[num].price = 0;
 61         
 62         Arrays.sort(stations, new Comparator<StationInfo>(){
 63             public int compare(StationInfo s1, StationInfo s2){
 64                 return (s1.dist - s2.dist < 0.0f) ? -1 : 1;
 65             }
 66         });
 67         
 68         for (int i = 0; i < stations.length - 1; i++){
 69             if (stations[i + 1].dist - stations[i].dist > longest_run){
 70                 float max_travel = stations[i].dist + longest_run;
 71                 System.out.println(String.format("The maximum travel distance = %.2f", max_travel));
 72                 return;
 73             }
 74         }
 75         
 76         if (stations[0].dist != 0.0f)
 77             System.out.println(String.format("The maximum travel distance = %.2f", 0.0f));
 78         
 79         int cur_station = 0;
 80         float cur_oil = 0.0f;
 81         float cost_sum = 0.0f;
 82         while (cur_station < num){
 83             float cur_run = 0.0f;
 84             int next_station = cur_station;
 85             int lowest_price_station = cur_station;
 86             float lowest_price = Float.MAX_VALUE;
 87             boolean solved = false;
 88             while (true){
 89                 float cur_dist = stations[next_station + 1].dist - stations[next_station].dist;
 90                 if (cur_dist + cur_run > longest_run)
 91                     break;
 92                 cur_run += cur_dist;
 93                 next_station++;
 94                 
 95                 if (stations[next_station].price < stations[cur_station].price){
 96                     float need_oil = cur_run / avg_dist;
 97                     float add_oil = (cur_oil > need_oil) ? 0.0f : (need_oil - cur_oil);
 98                     cost_sum += add_oil * stations[cur_station].price;
 99                     
100                     cur_oil = cur_oil + add_oil - need_oil;
101                     cur_station = next_station;
102                     
103                     solved = true;
104                     break;
105                 }
106                 
107                 /*
108                 if (next_station != cur_station){
109                     if (stations[next_station].price < lowest_price){
110                         lowest_price_station = next_station;
111                         lowest_price = stations[next_station].price;
112                     }
113                 }
114                 */
115             }
116             
117             if (!solved){
118                 float add_oil = cap - cur_oil;
119                 cost_sum += add_oil * stations[cur_station].price;
120                 cur_oil += add_oil;
121                 cur_oil -= cur_run / avg_dist;
122                 cur_station = next_station;
123             }
124         }
125         
126         System.out.println(String.format("%.2f", cost_sum));
127     }
128 }