ABC330F AC but long code

#include <assert.h>
#include <bits/stdc++.h>
using namespace std;
#ifndef __DEBUG__
#define dbg(...) 42
#endif
template <class T> using mpq = priority_queue<T, vector<T>, greater<T>>;

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vl = vector<ll>;
using vi = vector<int>;

int main(int argc, char **argv)
{
    ll n, k;
    cin >> n >> k;
    vl xs(n), ys(n), xacc(n + 2), yacc(n + 2);
    for (int i = 0; i < n; ++i)
        cin >> xs[i] >> ys[i];

    sort(xs.begin(), xs.end()), sort(ys.begin(), ys.end());
    for (int i = 0; i < n; ++i)
        xacc[i + 1] = xacc[i] + xs[i], yacc[i + 1] = yacc[i] + ys[i];

    auto find_k = [](ll d, const vl &as, const vl &acc) {
        ll ans = LLONG_MAX, n = as.size();
        for (ll i = 0, j = 0; i < n; ++i) {
            while (j < i && as[i] - as[j] > d)
                ++j;
            ll cost = (acc[n] - acc[i + 1]) - (n - i - 1) * as[i];
            cost += max(0ll, j * (as[i] - d) - acc[j]);
            ans = min(ans, cost);
        }
        for (ll i = 0, j = 0; i < n; ++i) {
            while (j < n && as[j] - as[i] <= d)
                ++j;
            ll cost = i * as[i] - acc[i];
            cost += acc[n] - acc[j] - (n - j) * (as[i] + d);
            ans = min(ans, cost);
        }
        return ans;
    };
    ll lb = -1, ub = 2e9;
    while (lb + 1 < ub) {
        ll mid = (lb + ub) / 2;
        ll fx = find_k(mid, xs, xacc), fy = find_k(mid, ys, yacc);
        // dbg(k, mid, fx, fy);
        (fx + fy > k ? lb : ub) = mid;
    }
    cout << ub << endl;
    return 0;
};