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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
2014-09-12 17:07:35 sidharth
accepted in CODECHEF, WA here -_-
2014-09-08 11:27:35 Diksha Meghwal
is the algorithm used dynamic?
2014-09-05 10:27:26 Gaurav Ahirwar
Learned lot of new things! :) ... NOTE: coins ordered in terms of increasing weight. This has not been mentioned in the question!
2014-07-28 08:54:10 priyanka agarwal
learn a lot!!
2014-04-27 13:10:32 Fendy
anyone know the constraint for T?
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
2011-12-30 18:04:10 lavish goel
@all : Rank1 has submit this in TEXT..??How any idea..??
--Pushing my head into wall--
--getting hurt--
2011-03-13 16:26:38 YatsukoYin
Nice problem! Thanks!
Solved in C# - got a lot of fun %)
2011-02-17 10:18:22 Antonin Karasek
Isn't this a MP complete problem? :-)
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