Submission #927725

#	Time	Username	Problem	Language	Result	Execution time	Memory
927725		Art_ogo	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	494 ms	55088 KiB

commuter_pass

#include <bits/stdc++.h>

/* #define int long long */ 
#define ll long long
#define fi first
#define se second
#define ve vector

using namespace std;

typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
#define all(x) x.begin(), x.end()

const int MAXN = 1e6+10;

ve<pll> g[MAXN];
ve<ll> ds, da, db, dt;
ll dpl[MAXN], dpr[MAXN], dp[MAXN];
bool vis[MAXN];

void djkstra(int s, ve<ll>& d){
    set<pll> st;
    st.insert({0, s});
    d[s] = 0;
    while(!st.empty()){
        int v = st.begin()->se;
        st.erase(st.begin());
        for(auto to : g[v]){
            if(d[to.fi] > d[v] + to.se){
                if(st.find({d[to.fi], to.fi}) != st.end())
                    st.erase({d[to.fi], to.fi});
                d[to.fi] = d[v] + to.se;
                st.insert({d[to.fi], to.fi});
            }
        }
    }
}

void dfsl(int v){
    vis[v] = 1;
    dpl[v] = da[v];
    for(auto& to : g[v]){
        if(ds[v] - to.se == ds[to.fi]){
            if(!vis[to.fi])
                dfsl(to.fi);
            dpl[v] = min(dpl[v], dpl[to.fi]);
        }
    }
}

void dfsr(int v){
    vis[v] = 1;
    dpr[v] = da[v];
    for(auto& to : g[v])      
        if(dt[v] - to.se == dt[to.fi]){
            if(!vis[to.fi])
               dfsr(to.fi);
            dpr[v] = min(dpr[v], dpr[to.fi]);
        }
    dp[v] = min(dpl[v], dpr[v]);
}

signed main(){
    int n, m;
    cin >> n >> m;
    int s, t, a, b;
    cin >> s >> t >> a >> b;
    s--; t--; a--; b--;
    for(int i = 0; i < m; i++){
        ll u, v, w;
        cin >> u >> v >> w;
        u--; v--;
        g[u].push_back({v, w});
        g[v].push_back({u, w});
    }
    ds.resize(n, 1e18);
    da.resize(n, 1e18);
    db.resize(n, 1e18);
    dt.resize(n, 1e18);
    fill(dpl, dpl + n, 1e18);
    fill(dpr, dpr + n, 1e18);
    fill(dp, dp + n, 1e18);
    djkstra(s, ds);
    djkstra(a, da);
    djkstra(b, db);
    djkstra(t, dt);
    dfsl(t);
    memset(vis, 0, sizeof(vis));
    dfsr(s);
    ll res = da[b];
    for(int i = 0; i < n; i++){
        res = min(res, dp[i] + db[i]);
    }
    cout << res;
}

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