Submission #1175865

#	Time	Username	Problem	Language	Result	Execution time	Memory
1175865		CodeLakVN	Palembang Bridges (APIO15_bridge)	C++17	100 / 100	88 ms	3520 KiB

bridge

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

#define task "15_bridge"
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define FOD(i, a, b) for (int i = (a); i >= (b); i--)
#define ll long long 
#define F first
#define S second

template<class X, class Y>
    bool minimize(X &x, Y y)  {
        if (x > y) {
            x = y;
            return true;
        }
        return false;
    }

typedef pair<int, int> ii;

int k, numCitizen;
vector<ii> citizen;
ll ans = 0;

namespace sub12 {
    vector<int> pos;

    void solve() {
        int n = (int)citizen.size();
        if (n == 0) {
            cout << ans << "\n";
            return;
        }
        FOR(i, 0, n - 1) {
            pos.push_back(citizen[i].F);
            pos.push_back(citizen[i].S);
        }

        sort(pos.begin(), pos.end());

        n = pos.size();
        int x = pos[n / 2];
        ll res = 0;
        for (ii p : citizen) {
            res += 1LL * abs(x - p.F) + 1LL * abs(x - p.S);
        }

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

namespace sub3 {
    vector<int> pos;

    void solve() {
        int n = (int)citizen.size();
        if (n == 0) {
            cout << ans << "\n";
            return;
        }
        FOR(i, 0, n - 1) {
            pos.push_back(citizen[i].F);
            pos.push_back(citizen[i].S);
        }

        sort(pos.begin(), pos.end());
        pos.erase(unique(pos.begin(), pos.end()), pos.end());

        ll res = LLONG_MAX;
        for (int x : pos) {
            for (int y : pos) {
                if (x == y) continue;
                ll cur = 0;
                for (ii p : citizen) {
                    cur += min(abs(x - p.F) + abs(x - p.S), abs(y - p.F) + abs(y - p.S));
                }
                minimize(res, cur);
            }
        }
        if (res == LLONG_MAX) res = 0;

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

namespace sub45 {
    bool cmp(ii &A, ii &B) {
        return A.F + A.S < B.F + B.S;
    }
    
    priority_queue<int> leftPQ;
    priority_queue<int, vector<int>, greater<int>> rightPQ;
    
    ll leftSum = 0, rightSum = 0;

    void insert(int x) {
        int median = ((int)leftPQ.size() ? leftPQ.top() : 1000000001);
        if (x < median) {
            leftPQ.push(x);
            leftSum += x;
        }
        else {
            rightPQ.push(x);
            rightSum += x;
        }

        if ((int)leftPQ.size() > (int)rightPQ.size() + 1) {
            int val = leftPQ.top();
            leftPQ.pop();
            rightPQ.push(val);
            leftSum -= val;
            rightSum += val;
        }
        else if ((int)rightPQ.size() > (int)leftPQ.size()) {
            int val = rightPQ.top();
            rightPQ.pop();
            leftPQ.push(val);
            rightSum -= val;
            leftSum += val;
        }
    }

    ll pre[100005];

    void solve() {
        if ((int)citizen.size() == 0) {
            cout << ans << "\n";
            return;
        }
        sort(citizen.begin(), citizen.end(), cmp);
        int n = (int)citizen.size();
        FOR(i, 0, n - 1) {
            insert(citizen[i].F);
            insert(citizen[i].S);
            pre[i + 1] = rightSum - leftSum;
        }
        ll res = LLONG_MAX;
        while ((int)leftPQ.size()) leftPQ.pop();
        while ((int)rightPQ.size()) rightPQ.pop();
        leftSum = rightSum = 0;
        FOD(i, n - 1, 0) {
            insert(citizen[i].F);
            insert(citizen[i].S);
            minimize(res, rightSum - leftSum + pre[i]);
        }

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

int main() {
    if (fopen(task".inp", "r")) {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    cin >> k >> numCitizen;
    FOR(i, 1, numCitizen) {
        char a, b;
        int x, y;
        cin >> a >> x >> b >> y;
        if (a == b) ans += 1LL * abs(x - y);
        else {
            ans++;
            citizen.push_back({x, y});
        }
    }

    if (k == 1) sub12::solve();
    else if (k == 2 && numCitizen <= 100) sub3::solve();
    else sub45::solve();

    return 0;
}

Compilation message (stderr)

bridge.cpp: In function 'int main()':
bridge.cpp:154:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  154 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
bridge.cpp:155:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  155 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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