Submission #998603

#	Time	Username	Problem	Language	Result	Execution time	Memory
998603		pannenkoek	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	187 ms	24224 KiB

commuter_pass

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

#define rep(i, a, b) for(int i = (a); i < (b); i++)
#define pb push_back
#define fi first
#define se second

using ll = long long;
using ld = long double;
using pii = pair<ll, ll>;

const int MAXN = 1e5 + 5;
const ll inf = 1e18 + 5;
int n, m, s, t, u, v, perm[MAXN];
vector<pii> adj[MAXN];
set<pii> marked;
bool vis1[MAXN], vis2[MAXN];
ll dis1[MAXN], dis2[MAXN], disu[MAXN], disv[MAXN], low1[MAXN], low2[MAXN];

ll dfs1(int i){
    if(vis1[i]) return low1[i];
    low1[i] = disv[i];
    vis1[i] = 1;
    for(auto [j, d]: adj[i]){
        if(dis1[i] + d + dis2[j] == dis1[t])
            low1[i] = min(low1[i], dfs1(j));
    }
    return low1[i];
}

ll dfs2(int i){
    if(vis2[i]) return low2[i];
    low2[i] = disv[i];
    vis2[i] = 1;
    for(auto [j, d]: adj[i]){
        if(dis2[i] + d + dis1[j] == dis1[t])
            low2[i] = min(low2[i], dfs2(j));
    }
    return low2[i];
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    cin >> n >> m >> s >> t >> u >> v;
    s--; t--; u--; v--;

    rep(i, 0, m){
        int a, b, c;
        cin >> a >> b >> c;
        a--; b--;
        adj[a].pb({b, c});
        adj[b].pb({a, c});
    }

    priority_queue<pii, vector<pii>, greater<pii>> pq;
    fill(dis1, dis1 + n, inf);
    dis1[s] = 0;
    pq.push({0, s});
    while(!pq.empty()){
        auto [d, cur] = pq.top();
        pq.pop();
        if(d > dis1[cur]) continue;
        for(auto [i, d2]: adj[cur]){
            if(d + d2 < dis1[i]){
                pq.push({d + d2, i});
                dis1[i] = d + d2;
            }
        }
    }
    fill(dis2, dis2 + n, inf);
    dis2[t] = 0;
    pq.push({0, t});
    while(!pq.empty()){
        auto [d, cur] = pq.top();
        pq.pop();
        if(d > dis2[cur]) continue;
        for(auto [i, d2]: adj[cur]){
            if(d + d2 < dis2[i]){
                pq.push({d + d2, i});
                dis2[i] = d + d2;
            }
        }
    }
    
    fill(disu, disu + n, inf);
    disu[u] = 0;
    pq.push({0, u});
    while(!pq.empty()){
        auto [d, cur] = pq.top();
        pq.pop();
        if(d > disu[cur]) continue;
        for(auto [i, d2]: adj[cur]){
            if(d + d2 < disu[i]){
                pq.push({d + d2, i});
                disu[i] = d + d2;
            }
        }
    }
    
    fill(disv, disv + n, inf);
    disv[v] = 0;
    pq.push({0, v});
    while(!pq.empty()){
        auto [d, cur] = pq.top();
        pq.pop();
        if(d > disv[cur]) continue;
        for(auto [i, d2]: adj[cur]){
            if(d + d2 < disv[i]){
                pq.push({d + d2, i});
                disv[i] = d + d2;
            }
        }
    }

    ll res = inf;
    rep(i, 0, n){
        res = min(res, dfs1(i) + disu[i]);
        res = min(res, dfs2(i) + disu[i]);
    }
    cout << res << "\n";

    return 0;
}

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