ZOJ 3699 Dakar Rally

Dakar Rally

---

Time Limit: 2 Seconds      Memory Limit: 65536 KB

---

Description

The Dakar Rally is an annual Dakar Series rally raid type of off-road race, organized by the Amaury Sport Organization. The off-road endurance race consists of a series of routes. In different routes, the competitors cross dunes, mud, camel grass, rocks, erg and so on.

Because of the various circumstances, the mileages consume of the car and the prices of gas vary from each other. Please help the competitors to minimize their payment on gas.

Assume that the car begins with an empty tank and each gas station has infinite gas. The racers need to finish all the routes in order as the test case descripts.

Input

There are multiple test cases. The first line of input contains an integer T (T ≤ 50) indicating the number of test cases. Then T test cases follow.

The first line of each case contains two integers: n -- amount of routes in the race; capacity -- the capacity of the tank.

The following n lines contain three integers each: mileage_i -- the mileage of the i^th route; consume_i -- the mileage consume of the car in the i^th route , which means the number of gas unit the car consumes in 1 mile; price_i -- the price of unit gas in the gas station which locates at the beginning of the i^th route.

All integers are positive and no more than 10⁵.

Output

For each test case, print the minimal cost to finish all of the n routes. If it's impossible, print "Impossible" (without the quotes).

Sample Input

2
2 30
5 6 9
4 7 10
2 30
5 6 9
4 8 10

Sample Output

550
Impossible

---

Author: OUYANG, Jialin
Contest: The 13th Zhejiang University Programming Contest

用一个双端队列维护，使容量为C的油箱中，便宜的油的比例最大，并优先使用便宜的油。。。。

 #include <iostream>
 #include <cstring>
 #include <cstdio>
 #include <queue>
 #include <deque>
 #include <cmath>

 using namespace std;

 typedef long long int LL;

 struct ROAD
 {
     int m,c,p,cpm;
 }road[];

 struct OIL
 {
     int P,L;
     bool operator<(OIL t) const
     {
         return P>t.P;
     }
 };

 int N,C,t;

 LL solve()
 {
     LL ret=;
     int vol=;///zhong gong C L de you
     deque<OIL> dq;
     for(int i=;i<=N;i++)
     {
         while(vol&&!dq.empty()&&dq.back().P>road[i].p)
         {
             vol-=dq.back().L;
             dq.pop_back();
         }
         OIL t; t.L=C-vol; t.P=road[i].p;
         vol=C-road[i].cpm;
         dq.push_back(t);
         int youliang=road[i].cpm;
         while(youliang>)
         {
             OIL& cur=dq.front();
             int Minn=min(cur.L,youliang);
             ret+=(LL)Minn*cur.P;
             youliang-=Minn; cur.L-=Minn;
             if(!cur.L) dq.pop_front();
         }
     }
     return ret;
 }

 int main()
 {
     scanf("%d",&t);
     while(t--)
     {
         scanf("%d%d",&N,&C);
         bool flag=true;
         for(int i=;i<=N;i++)
         {
             scanf("%d%d%d",&road[i].m,&road[i].c,&road[i].p);
             road[i].cpm=road[i].c*road[i].m;
             if(road[i].cpm>C) flag=false;
         }
         if(flag==false) puts("Impossible");
         else printf("%lld\n",solve());
     }
     return ;
 }