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Problem E: Lowest Price in Town |
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Time limit: 1 second |
It is sometimes tricky to figure out the cheapest way to buy things, even in the supermarket where the price of all goods are listed clearly. Just consider what I saw last Saturday about the price of cooking oil: (notice the difference in the sizes of the two price tags)
Having a sharp mind (a consequence of regularly taking part in online programming contests), you should have no problem in seeing that the 'buy-1-get-1-free' scheme is preferable. But what about your Mum? It is your responsibility as her son/daughter to write her a program that computes the lowest price to buy things in the supermarket, thus helps her to save money.
The input consists of more than a hundred test cases, each concerning a different item. The first line of each case gives the unit price of buying an item, then a non-negative integer M (≤ 20). This is followed by M lines each containing two numbers N and P (1 < N ≤ 100), which means that you can buy N such items for $P. Finally there is a line containing a list of positive integers K (≤ 100); for each of them your program should print the lowest price you need to get K items. Note that you do not have to buy exactly K items; you may consider buying more than K items, and giving the unneeded items to your dear neighbours, if you can save money in this way.
Note that all prices P given in the input are floating-point numbers in exactly 2 decimal places, with 0 < P < 1000.
22.00 2 2 22.00 4 60.00 2 4 25.00 2 2 48.00 2 46.00 2 22.00 2 2 22.00 4 40.00 1 2 3
Case 1: Buy 2 for $22.00 Buy 4 for $44.00 Case 2: Buy 2 for $46.00 Case 3: Buy 1 for $22.00 Buy 2 for $22.00 Buy 3 for $40.00