转载注明出处：http://www.cnblogs.com/ligun123/archive/2013/03/26/2982472.html
题目来源：https://www.hackerrank.com/challenges/flowers
You and your K-1 friends want to buy N flowers. Flower number i has cost ci. Unfortunately the seller does not like a customer to buy a lot of flowers, so he tries to change the price of flowers for customer who had bought flowers before. More precisely if a customer has already bought x flowers, he should pay (x+1)*ci dollars to buy flower number i.
You and your K-1 firends want to buy all N flowers in such a way that you spend as less money as possible.
Input:
The first line of input contains two integers N and K (K <= N) next line contains N positive integers c1,c2,…,cN respectively.
Output:
Print the minimum amount of money you (and your friends) have to pay in order to buy all N flowers.
Sample input :
3 3
2 5 6
Sample output :
13
Explanation :
In the example each of you and your friends should buy one flower. in this case you have to pay 13 dollars.
Constraint :
1 <= N, K <= 100
Each ci is not more than 1000,000
不贴代码，说说思路，很简单，先买最贵的，再买最便宜的~