interviewstreet - Flowers 类别Search

题目来源：https://www.interviewstreet.com/challenges/dashboard/#problem/4fd05444acc45、

解题报告：

把花的价钱进行排序，那么K个人一定最先买最贵的K朵花，然后依次往便宜的去买。

#include 
#include 
using namespace std;

int c[100];
int main()
{
    int N, K;
    cin >> N >> K;
    for (int i = 0; i < N; i++)
    {
        cin >> c[i];
    }
    sort(c, c+N);
    long long sum = 0;
    int x = 1;
    for (int i = N-1; i >=0; i -= K)
    {
        for (int j = i; j >= 0 && j > i-K; j--)
            sum += x * c[j];
        x++;
    }
    cout << sum << endl;
}

附录：

You and your K-1 friends want to buy N flowers. Flower number i has host c_i. 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)*c_i 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 the as few money as possible.

Input:

The first line of input contains two integers N and K.
next line contains N positive integers c₁,c₂,...,c_N respectively.

Output:

Print the minimum amount of money you (and your friends) have to pay in order to buy all n flowers.

Sample onput :

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 c_i is not more than 1000,000