Submission #1312704

#	Time	Username	Problem	Language	Result	Execution time	Memory
1312704		btkhg	Palembang Bridges (APIO15_bridge)	C++20	63 / 100	2093 ms	4176 KiB

bridge

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

ll one_bridge_cost(const vector<pair<ll,ll>>& segs) {
    vector<ll> pts;
    pts.reserve(segs.size() * 2);
    for (auto &p : segs) {
        pts.push_back(p.first);
        pts.push_back(p.second);
    }
    sort(pts.begin(), pts.end());
    ll x = pts[pts.size() / 2];

    ll cost = 0;
    for (auto &p : segs) {
        cost += llabs(p.first - x) + llabs(p.second - x) + 1;
    }
    return cost;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int K, N;
    cin >> K >> N;

    ll answer = 0;
    vector<pair<ll,ll>> cross;

    for (int i = 0; i < N; i++) {
        char P, Q;
        ll S, T;
        cin >> P >> S >> Q >> T;

        if (P == Q) {

            answer += llabs(S - T);
        } else {
           
            ll L = min(S, T);
            ll R = max(S, T);
            cross.push_back({L, R});
        }
    }

    if (cross.empty()) {
        cout << answer << "\n";
        return 0;
    }

    if (K == 1) {
        answer += one_bridge_cost(cross);
        cout << answer << "\n";
        return 0;
    }


    int M = cross.size();

    sort(cross.begin(), cross.end(), [](auto &a, auto &b){
        return (a.first + a.second) < (b.first + b.second);
    });

    vector<ll> pref(M), suff(M);

    for (int i = 0; i < M; i++) {
        vector<pair<ll,ll>> tmp(cross.begin(), cross.begin() + i + 1);
        pref[i] = one_bridge_cost(tmp);
    }

    for (int i = M - 1; i >= 0; i--) {
        vector<pair<ll,ll>> tmp(cross.begin() + i, cross.end());
        suff[i] = one_bridge_cost(tmp);
    }

    ll best = LLONG_MAX;
    for (int i = 0; i + 1 < M; i++) {
        best = min(best, pref[i] + suff[i + 1]);
    }

    answer += best;
    cout << answer << "\n";
    return 0;
}

• Subtask 1: 8 / 8
• Subtask 2: 14 / 14
• Subtask 3: 9 / 9
• Subtask 4: 32 / 32
• Subtask 5: 0 / 37