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SPOJ Problem Set (classical)

39. Piggy-Bank

Problem code: PIGBANK

Before ACM can do anything, a budget must be prepared and the necessary financial support obtained. The main income for this action comes from Irreversibly Bound Money (IBM). The idea behind is simple. Whenever some ACM member has any small money, he takes all the coins and throws them into a piggy-bank. You know that this process is irreversible, the coins cannot be removed without breaking the pig. After a sufficiently long time, there should be enough cash in the piggy-bank to pay everything that needs to be paid.

But there is a big problem with piggy-banks. It is not possible to determine how much money is inside. So we might break the pig into pieces only to find out that there is not enough money. Clearly, we want to avoid this unpleasant situation. The only possibility is to weigh the piggy-bank and try to guess how many coins are inside. Assume that we are able to determine the weight of the pig exactly and that we know the weights of all coins of a given currency. Then there is some minimum amount of money in the piggy-bank that we can guarantee. Your task is to find out this worst case and determine the minimum amount of cash inside the piggy-bank. We need your help. No more prematurely broken pigs!


The input consists of T test cases. The number of them (T) is given on the first line of the input file. Each test case begins with a line containing two integers E and F. They indicate the weight of an empty pig and of the pig filled with coins. Both weights are given in grams. No pig will weigh more than 10 kg, that means 1 <= E <= F <= 10000. On the second line of each test case, there is an integer number N (1 <= N <= 500) that gives the number of various coins used in the given currency. Following this are exactly N lines, each specifying one coin type. These lines contain two integers each, Pand W (1 <= P <= 50000, 1 <= W <=10000). P is the value of the coin in monetary units, W is it's weight in grams.


Print exactly one line of output for each test case. The line must contain the sentence "The minimum amount of money in the piggy-bank is X." where X is the minimum amount of money that can be achieved using coins with the given total weight. If the weight cannot be reached exactly, print a line "This is impossible.".


Sample Input:

10 110
1 1
30 50
10 110
1 1
50 30
1 6
10 3
20 4

Sample output:

The minimum amount of money in the piggy-bank is 60.
The minimum amount of money in the piggy-bank is 100.
This is impossible.

Added by:Adrian Kosowski
Time limit:5s
Source limit:50000B
Memory limit:256MB
Cluster: Pyramid (Intel Pentium III 733 MHz)
Resource:ACM Central European Programming Contest, Prague 1999

hide comments
2014-04-01 23:14:34 galactocalypse
@admin: The specified limits seem incorrect.

Using 10050 for F-E and 600 for N got my solution AC. 10001 and 501 led to SIGSEGV.

My bad. Test cases are fine.

Last edit: 2014-04-01 23:17:59
2014-03-23 15:23:55 ||N0VICE||
nice problem
learn something
3rd DP
2014-03-21 08:34:27 Raj Mehta
i am getting TLE anyone can let me know how can i improve
2014-03-02 17:23:30 Anchal Gupta
dp!!! my 50th
2014-02-17 19:10:21 nitesh kumar
2014-01-17 10:18:30 Karan Puri
@on the hell Opting for the greedy approach at every step might lead you to no answer for most of the cases.
Because, for the following case
0 5
2 2
4 3

Here by greedy, you will pick 2 first, then you'll pick 2 again and hence you'll be left with '1' and you wont be able to fill that.
2014-01-17 10:14:58 Karan Puri
In the output, is there any particular way, the new lines are supposed to be.
Shall we add newLine in the front of it, or on the end of it (leaving the last one)
2014-01-17 10:13:12 Karan Puri
The heck, got answer approved on Codechef for the same problem, but not here?
People you can check your's here. http://www.codechef.com/problems/PD22
2014-01-15 08:02:29 on the hell
can some body explain why greedy won't work here ?
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