Submission #623610

#	Time	Username	Problem	Language	Result	Execution time	Memory
623610		BhavayGoyal	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	313 ms	27232 KiB

commuter_pass

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

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;

template<class T> using oset = 
            tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

#define int long long
#define ld long double
#define ar array
#define vi vector<int>
#define vii vector<vector<int>>
#define pii pair<int, int>
#define pb push_back
#define all(x) x.begin(), x.end()
#define f first
#define s second
#define endl "\n"

const int MOD = 1e9+7;
const int inf = 1e16;

const int d4i[4]={-1, 0, 1, 0}, d4j[4]={0, 1, 0, -1};
const int d8i[8]={-1, -1, 0, 1, 1, 1, 0, -1}, d8j[8]={0, 1, 1, 1, 0, -1, -1, -1};


// -------------------------------------------------- Main Code --------------------------------------------------

const int N = 1e5;
int n, m, s, t, u, v; 
vector<array<int, 2>> g[N];
vi du(N, inf), dv(N, inf), dpu(N, inf), dpv(N, inf), dis(N, inf);
int ans = inf;

void dijkstra(int src, vi &distance) {
    distance[src] = 0;
    priority_queue<pii, vector<pii>, greater<pii>> q;
    q.push({0, src});
    while (!q.empty()) {
        int dist = q.top().f, src = q.top().s; q.pop();
        for (auto ch : g[src]) {
            if (ch[1]+dist < distance[ch[0]]) {
                distance[ch[0]] = ch[1]+dist;
                q.push({distance[ch[0]], ch[0]});
            }
        }
    }
}

void dijkstra2(int src, int end) {
    dpu = vi(n, inf); dpv = vi(n, inf);
    priority_queue<array<int, 3>, vector<array<int, 3>>, greater<array<int, 3>>> q;
    q.push({0, src, src});
    vi vis(n, 0);
    while (!q.empty()) {
        int dist = q.top()[0], src = q.top()[1], par = q.top()[2]; q.pop();
        if (!vis[src]) {
            vis[src] = true;
            dis[src] = dist;
            dpu[src] = min(dpu[par], du[src]);
            dpv[src] = min(dpv[par], dv[src]);
            for (auto ch : g[src]) q.push({dist+ch[1], ch[0], src});
        }
        else if (dis[src] == dist) {
            if (min(dpu[par], du[src]) + min(dpv[par], dv[src]) <= dpu[src]+dpv[src]) {
                dpu[src] = min(dpu[par], du[src]);
                dpv[src] = min(dpv[par], dv[src]);
            }
        }
    }
    ans = min(ans, dpu[end]+dpv[end]);
}

void sol() {
    cin >> n >> m >> s >> t >> u >> v; --s; --t; --u; --v;
    for (int i = 0; i < m; i++) {
        int a, b, c; cin >> a >> b >> c;
        g[--a].pb({--b, c});
        g[b].pb({a, c});
    }

    dijkstra(u, du);
    dijkstra(v, dv);

    ans = du[v];

    dijkstra2(s, t);

    cout << ans << endl;
}

signed main () {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t = 1;
    // cin >> t; 
    while (t--) {
        sol();
    }
    return 0;
}

• Subtask 1: 16 / 16
• Subtask 2: 15 / 15
• Subtask 3: 24 / 24
• Subtask 4: 45 / 45