Submission #943681

#	Time	Username	Problem	Language	Result	Execution time	Memory
943681		HiepVu217	Palembang Bridges (APIO15_bridge)	C++17	Compilation error	0 ms	0 KiB

bridge

#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 17;
int k, n;
long long s[N], ans, ls, rs;
priority_queue <int> lpq, rpq;
vector <pair <int, int>> vt;
bool cmp (pair <int, int> x, pair <int, int> y)
{
    return x.first + x.second < y.first + y.second;
}
void add (int x)
{
    int mid;
    if (lpq.size())
    {
        mid = lpq.top();
    }
    else
    {
        mid = 1e9 + 17;
    }
    if (x <= mid)
    {
        lpq.push(x);
        ls += x;
    }
    else
    {
        rpq.push(-x);
        rs += x;
    }
    if (lpq.size() > rpq.size() + 1)
    {
        int t = lpq.top();
        lpq.pop();
        ls -= t;
        rpq.push(-t);
        rs += t;
    }
    if (rpq.size() > lpq.size())
    {
        int t = -rpq.top();
        rpq.pop();
        rs -= t;
        lpq.push(t);
        ls += t;
    }
}
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> k >> n;
    long long z = 0;
    vt.push_back ({0, 0});
    for (int i = 1; i <= n; ++i)
    {
        int a, b;
        char x, y;
        cin >> x >> a >> y >> b;
        if (x == y)
        {
            z += abs (a - b);
            continue;
        }
        vt.push_back ({a, b});
    }
    sort (vt.begin(), vt.end(), cmp);
    n = vt.size() - 1;
    z += n;
    for (int i = 1; i <= n; ++i)
    {
        add (vt[i].first);
        add (vt[i].second);
        s[i] = rs - ls;
    }
    ans = s[n];
    if (k == 2)
    {
		while (lpq.size())
        {
            lpq.pop();
        }
		while (rpq.size())
        {
            rpq.pop();
        }
		ls = rs = 0;
		for (int i = n; i > 0; i--)
        {
			add (vt[i].first);
			add (vt[i].second);
			ans = min (ans, rs - ls + pref[i - 1]);
		}
	}
    cout << ans + z;
}

Compilation message (stderr)

bridge.cpp: In function 'int main()':
bridge.cpp:95:30: error: 'pref' was not declared in this scope
   95 |    ans = min (ans, rs - ls + pref[i - 1]);
      |                              ^~~~