题目： 

 

翻译： 

 思路：

1、将数据从大到小排序

2、用前缀和

3、每次用总和减去2倍的乘-1的数，求最大值

代码：

#include <iostream>
#include<algorithm>
using namespace std;

void solve() {
    int n, k, x;
    cin >> n >> k >> x;

    int A[200020] = {};
    for (int i = 1; i <= n; i++)
        cin >> A[i];

    sort(A + 1, A + n + 1, greater<int>());//降序排列

    for (int i = 1; i <= n; i++)
        A[i] += A[i - 1];

    int ans = -1e9;
    for (int i = 0; i <= k; i++)
        ans = max(ans, (A[n] - 2 * A[min(i + x, n)] + A[i]));

    cout << ans << "\n";
}

int main() 
{
    int tc;
    cin >> tc;

    while (tc--)
        solve();
}