CheapestGifts | Topcoder Archive

Problem Statement

You have k friends and you would like to buy each of them a gift. Since you are short of money, you would like to minimize the total cost.

You go to a store that has n different products. There are exactly m of each product available in stock. Given a int[] prices containing the price of each product, return the minimum possible total cost to buy k gifts. If there are not enough gifts in the store, return -1.

Definition

Class:: CheapestGifts
Method:: getPrice
Parameters:: int[], int, int
Returns:: int
Method signature:: int getPrice(int[] prices, int m, int k)
(be sure your method is public)

Constraints

prices will contain between 1 and 50 elements, inclusive.
Each element of prices will be between 1 and 1000, inclusive.
m will be between 1 and 1000, inclusive.
k will be between 1 and 100,000, inclusive.

Examples

```
{1,3,2}
```
```
2
```
```
3
```
```
Returns: 4
```
You can buy two gifts with a price of 1 each and one gift with a price of 2 for a total cost of 4.
```
{1}
```
```
2
```
```
3
```
```
Returns: -1
```
There is only one product and the store only has two of it in stock. You need three gifts, so you return -1.
```
{1, 2, 3, 4, 5, 6, 7}
```
```
1
```
```
7
```
```
Returns: 28
```
In this case you must buy all the gifts in the store.

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