Code

#include <bits/stdc++.h>
using namespace std;

long long minus_inf = -1 * (long long)1e15;

long long solve(vector<long long> &a, int n) {

    vector<long long> end_before_or_at(3 * n), start_at_or_after(3 * n);

    priority_queue<long long, vector<long long>, greater<long long>> minHeap;

    long long largest_n_sum = 0;
    for (int i = 0; i < n; i++) {
        minHeap.push(a[i]);
        largest_n_sum += a[i];
    }
    end_before_or_at[n - 1] = largest_n_sum;

    for (int i = n; i < 2 * n; i++) {
        minHeap.push(a[i]);
        largest_n_sum += a[i];

        largest_n_sum -= minHeap.top();
        minHeap.pop();

        end_before_or_at[i] = largest_n_sum;
    }

    priority_queue<long long> maxHeap;
    long long smallest_n_sum = 0;

    for (int i = 3 * n - 1; i >= 2 * n; i--) {
        maxHeap.push(a[i]);
        smallest_n_sum += a[i];
    }

    start_at_or_after[2 * n] = smallest_n_sum;
    for (int i = 2 * n - 1; i >= n; i--) {
        maxHeap.push(a[i]);
        smallest_n_sum += a[i];

        smallest_n_sum -= maxHeap.top();
        maxHeap.pop();

        start_at_or_after[i] = smallest_n_sum;
    }

    vector<long long> dp(3 * n, minus_inf);
    for (int i = n - 1; i < 2 * n; i++) {
        dp[i] = end_before_or_at[i] - start_at_or_after[i + 1];
    }

    return *max_element(dp.begin(), dp.end());
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int n;
    cin >> n;
    vector<long long> a(3 * n);
    for (int i = 0; i < 3 * n; i++) {
        cin >> a[i];
    }

    long long res = solve(a, n);
    cout << res << endl;

    return 0;
}

#include <bits/stdc++.h>
using namespace std;

long long minus_inf = -1 * (long long)1e15;

long long solve(vector<long long> &a, int n) {

    vector<long long> end_before_or_at(3 * n), start_at_or_after(3 * n);

    for (int i = n - 1; i < 2 * n; i++) {
        priority_queue<long long> maxHeap;
        for (int j = 0; j <= i; j++) {
            maxHeap.push(a[j]);
        }

        long long largest_n_sum = 0;
        for (int k = 0; k < n; k++) {
            largest_n_sum += maxHeap.top();
            maxHeap.pop();
        }
        end_before_or_at[i] = largest_n_sum;
    }

    for (int i = n; i < 2 * n + 1; i++) {
        priority_queue<long long, vector<long long>, greater<long long>>
            minHeap;
        for (int j = i; j < 3 * n; j++) {
            minHeap.push(a[j]);
        }

        long long smallest_n_sum = 0;
        for (int k = 0; k < n; k++) {
            smallest_n_sum += minHeap.top();
            minHeap.pop();
        }
        start_at_or_after[i] = smallest_n_sum;
    }

    vector<long long> dp(3 * n, minus_inf);
    for (int i = n - 1; i < 2 * n; i++) {
        dp[i] = end_before_or_at[i] - start_at_or_after[i + 1];
    }

    return *max_element(dp.begin(), dp.end());
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int n;
    cin >> n;
    vector<long long> a(3 * n);
    for (int i = 0; i < 3 * n; i++) {
        cin >> a[i];
    }

    long long res = solve(a, n);
    cout << res << endl;

    return 0;
}