Submission #348535

#	Time	Username	Problem	Language	Result	Execution time	Memory
348535		Mahdi_Shokoufi	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	530 ms	38288 KiB

commuter_pass

//In the name of Allah
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair < int , int > pii;
typedef pair < ll , ll > pll;

#define X first
#define Y second
#define mp make_pair
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x.size())

const int N = 1e5 + 10;
const ll mod = 1e9 + 7;
const ll inf = 1e18 + 10;

int S, T, U, V, mark[N];
ll ds[N], dt[N], du[N], dv[N], dpu[N], dpv[N], ans;
vector < pll > adj[N];
vector < int > dag[N], dag2[N], vec;
priority_queue < pll , vector < pll > , greater < pll > > pq;

void dij(int s, ll *dis){
    fill(dis, dis + N, inf);
    dis[s] = 0;
    pq.push(mp(0, s));
    while (sz(pq)){
        ll v = pq.top().Y, c = pq.top().X;
        pq.pop();
        if (c != dis[v])
            continue;
        for (pll e : adj[v]){
            ll u = e.X, w = e.Y;
            ll cp = c + w;
            if (cp < dis[u]){
                dis[u] = cp;
                pq.push(mp(dis[u], u));
            }
        }
    }
}

void dfs(int v){
    mark[v] = 1;
    for (int u : dag[v])
        if (!mark[u])
            dfs(u);
    vec.pb(v);
}


void dfs2(int v){
    mark[v] = 1;
    for (int u : dag2[v])
        if (!mark[u])
            dfs2(u);
    vec.pb(v);
}


int main(){
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    int n, m;
    cin >> n >> m >> S >> T >> U >> V;
    for (int i = 0; i < m; i ++){
        int u, v, w;
        cin >> u >> v >> w;
        adj[u].pb(mp(v, w));
        adj[v].pb(mp(u, w));
    }
    dij(S, ds);
    dij(T, dt);
    dij(U, du);
    dij(V, dv);
    for (int i = 1; i <= n; i ++)
        for (pll e : adj[i])
            if (ds[i] + e.Y == ds[e.X])
                dag[i].pb(e.X);
    for (int i = 1; i <= n; i ++)
        for (pll e : adj[i])
            if (dt[i] + e.Y == dt[e.X])
                dag2[i].pb(e.X);
    fill(dpu, dpu + N, inf);
    fill(dpv, dpv + N, inf);
    ans = du[V];
    dfs(S);
    reverse(all(vec));
    for (int v : vec){
        dpu[v] = min(dpu[v], du[v]);
        dpv[v] = min(dpv[v], dv[v]);
        if (ds[v] + dt[v] == ds[T]){
            ans = min(ans, du[v] + dpv[v]);
            ans = min(ans, dv[v] + dpu[v]);
        }
        for (int u : dag[v]){
            dpu[u] = min(dpu[u], dpu[v]);
            dpv[u] = min(dpv[u], dpv[v]);
        }
    }
    vec.clear();
    fill(mark, mark + N, 0);
    fill(dpu, dpu + N, inf);
    fill(dpv, dpv + N, inf);
    dfs2(T);
    reverse(all(vec));
    for (int v : vec){
        dpu[v] = min(dpu[v], du[v]);
        dpv[v] = min(dpv[v], dv[v]);
        if (ds[v] + dt[v] == ds[T]){
            ans = min(ans, du[v] + dpv[v]);
            ans = min(ans, dv[v] + dpu[v]);
        }
        for (int u : dag2[v]){
            dpu[u] = min(dpu[u], dpu[v]);
            dpv[u] = min(dpv[u], dpv[v]);
        }
    }
    cout << ans;
    return 0;
}

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