Submission #475717

#	Time	Username	Problem	Language	Result	Execution time	Memory
475717		CodeChamp_SS	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	951 ms	35980 KiB

commuter_pass

#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;

#define ff                  first
#define ss                  second
#define pb                  push_back
#define eb                  emplace_back
#define mp                  make_pair
#define lb                  lower_bound
#define ub                  upper_bound
#define setbits(x)          __builtin_popcountll(x)
#define zrobits(x)          __builtin_ctzll(x)
#define sz(v)               (int)v.size()
#define ps(y)               cout << fixed << setprecision(y)
#define ms(arr, v)          memset(arr, v, sizeof(arr))
#define all(v)              v.begin(), v.end()
#define rall(v)             v.rbegin(), v.rend()
#define trav(x, v)          for(auto &x: v)
#define w(t)                int t; cin >> t; while(t--)
#define rep(i, a, b)        for(int i = a; i <= b; i++)
#define rrep(i, a, b)       for(int i = a; i >= b; i--)
#define rep0(i, n)          rep(i, 0, n - 1)
#define rrep0(i, n)         rrep(i, n - 1, 0)
#define rep1(i, n)          rep(i, 1, n)
#define rrep1(i, n)         rrep(i, n, 1)
#define inp(arr, n)         rep0(i, n) cin >> arr[i];

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll, ll> pii;
typedef vector<ll> vi;
typedef vector<vi> vvi;
typedef vector<pii> vp;
typedef vector<bool> vb;
typedef vector<string> vs;
typedef map<ll, ll> mii;
typedef map<char, ll> mci;
typedef priority_queue<ll> pq_mx;
typedef priority_queue<vi, vvi, greater<>> pq_mn;
typedef tree<ll, null_type, less<>, rb_tree_tag, tree_order_statistics_node_update> pbds;
/*
 * find_by_order(i) -> returns an iterator to the element at ith position (0 based)
 * order_of_key(i)  -> returns the position of element i (0 based)
 */

const int N = 2e5 + 5;
const int mod = 1e9 + 7;
//const int mod = 998244353;
const ll inf = 1e18;
const double eps = 1e-10;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

void fio() {
    ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
}

int n, m, S, T, U, V;
ll dp[2][N], res;
vi du, dv;
vp gr[N];

vi dijkstra(int src) {
    vi dist(n + 1, inf);
    dist[src] = 0;
    set<pii> q;
    q.emplace(0, src);
    while (!q.empty()) {
        auto[d, cur] = *q.begin();
        q.erase(q.begin());
        trav(neigh, gr[cur]) {
            if (dist[neigh.ff] > d + neigh.ss) {
                auto it = q.find({dist[neigh.ff], neigh.ff});
                if (it != q.end()) q.erase(it);
                dist[neigh.ff] = d + neigh.ss, q.emplace(dist[neigh.ff], neigh.ff);
            }
        }
    }
    return dist;
}

void f(ll s, ll e) {
    rep0(i, 2) {
        rep0(x, n + 1) dp[i][x] = inf;
    }
    vi dist(n + 1, inf);
    vb vis(n + 1, false);
    pq_mn q;
    q.push({0, s, 0});
    while (!q.empty()) {
        vi v = q.top();
        q.pop();
        ll d = v[0], cur = v[1], par = v[2];
        if (!vis[cur]) {
            vis[cur] = true, dist[cur] = d;
            dp[0][cur] = min(du[cur], dp[0][par]);
            dp[1][cur] = min(dv[cur], dp[1][par]);
            trav(neigh, gr[cur]) q.push({d + neigh.ss, neigh.ff, cur});
        } else if (dist[cur] == d) {
            if (min(dp[0][par], du[cur]) + min(dp[1][par], dv[cur]) <= dp[0][cur] + dp[1][cur]) {
                dp[0][cur] = min(du[cur], dp[0][par]);
                dp[1][cur] = min(dv[cur], dp[1][par]);
            }
        }
    }

    res = min(res, dp[0][e] + dp[1][e]);
}


int main() {
    fio();

    cin >> n >> m >> S >> T >> U >> V;
    rep0(x, m) {
        int u, v, w;
        cin >> u >> v >> w;
        gr[u].eb(v, w), gr[v].eb(u, w);
    }
    du = dijkstra(U), dv = dijkstra(V);
    res = du[V];
    f(S, T), f(T, S);
    cout << res;

    return 0;
}

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