Submission #1080669

#	Time	Username	Problem	Language	Result	Execution time	Memory
1080669		asdasdqwer	Shortcut (IOI16_shortcut)	C++14	23 / 100	2047 ms	444 KiB

shortcut

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

#include "shortcut.h"

#define ll long long int
#define pii array<ll, 2>
#define tii array<ll,3>

ll dijkstra(vector<vector<pii>> &g, int source, vector<int> &d) {
    int n=(int)g.size();
    vector<ll> dis(n, (ll)1e16);
    dis[source]=d[source];
    priority_queue<pii> pq;
    pq.push({-dis[source], source});
    vector<bool> vis(n, false);
    while (!pq.empty()) {
        auto [d, node] = pq.top();pq.pop();
        if (vis[node]) continue;
        vis[node]=true;

        for (auto [ne, we] : g[node]) {
            if ((dis[node] + we) < dis[ne]) {
                dis[ne] = dis[node] + we;
                pq.push({-dis[ne], ne});
            }
        }
    }

    ll mx = 0;
    for (int i=0;i<n;i++) {
        if (i == source) continue;
        mx = max(mx, dis[i] + (ll)d[i]);
    }
    return mx;
}

ll diameter(vector<vector<pii>> &g, vector<int> &d) {
    ll dis = 0;
    for (int i=0;i<(int)g.size();i++) {
        dis = max(dis, dijkstra(g, i, d));
    }
    return dis;
}

long long find_shortcut(int n, std::vector <int> l, std::vector <int> d, int c) {
    int tmp = n;
    for (int i=0;i<n;i++)if (d[i]) tmp++;
    vector<vector<pii>> g(n);
    for (int i=0;i<n-1;i++) {
        g[i].push_back({i+1, (ll)l[i]});
        g[i+1].push_back({i, (ll)l[i]});
    }

    ll mxDis = 1e16;

    for (int i=0;i<n;i++) {
        for (int j=i+1;j<n;j++) {
            g[i].push_back({j, (ll)c});
            g[j].push_back({i, (ll)c});
            mxDis = min(mxDis, diameter(g, d));
            g[i].pop_back();
            g[j].pop_back();
        }
    }

    return mxDis;
}

// long long find_shortcut(int n, std::vector <int> l, std::vector <int> d, int c) {
//     int tmp = n;
//     for (int i=0;i<n;i++)if (d[i]) tmp++;
//     vector<vector<pii>> g(tmp);
//     for (int i=0;i<n-1;i++) {
//         g[i].push_back({i+1, (ll)l[i]});
//         g[i+1].push_back({i, (ll)l[i]});
//     }

//     int lst = n;
//     vector<int> child(n, -1), parent(n, -1);
//     for (int i=0;i<n;i++) {
//         if (d[i] == 0) continue;
//         g[i].push_back({lst, (ll)d[i]});
//         g[lst].push_back({i, (ll)d[i]});
//         child[i] = lst;
//         parent[lst-n] = i;
//         lst++;
//     }

//     // get diameter pair
//     tii pr = diameter(g);
//     // cout << pr[0]-n << " " << pr[1]-n << "\n";
//     // cout << pr[2] << "\n";
//     for (int i=0;i<2;i++) {
//         if (pr[i] >= n) pr[i] = parent[pr[i]-n];
//     }

//     // cout << pr[0] << " " << pr[1] << "\n";

//     vector<ll> al = {0, n-1, pr[0], pr[1]};
//     sort(al.begin(), al.end());
//     al.erase(unique(al.begin(), al.end()), al.end());

//     ll diam = pr[2];
//     for (int i=0;i<(int)al.size();i++) {
//         for (int j=0;j<n;j++) {
//             if (j == al[i]) continue;
//             g[al[i]].push_back({j, c});
//             g[j].push_back({al[i], c});

//             diam = min(diam, diameter(g)[2]);
//             g[al[i]].pop_back();g[j].pop_back();
//         }
//     }

//     return diam;
// }

Compilation message (stderr)

shortcut.cpp: In function 'long long int dijkstra(std::vector<std::vector<std::array<long long int, 2> > >&, int, std::vector<int>&)':
shortcut.cpp:18:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   18 |         auto [d, node] = pq.top();pq.pop();
      |              ^
shortcut.cpp:22:19: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   22 |         for (auto [ne, we] : g[node]) {
      |                   ^

• Subtask 1: 9 / 9
• Subtask 2: 14 / 14
• Subtask 3: 0 / 8
• Subtask 4: 0 / 7
• Subtask 5: 0 / 33
• Subtask 6: 0 / 22
• Subtask 7: 0 / 4
• Subtask 8: 0 / 3