Submission #1087643

#	Time	Username	Problem	Language	Result	Execution time	Memory
1087643		FubuGold	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	220 ms	32540 KiB

commuter_pass

#include<bits/stdc++.h>
#define int long long
#define pii pair<int,int>

using namespace std;

const int maxn = 1e5 + 2;
const int inf = LLONG_MAX / 4;

int n,m,ans=inf;
int D,S,T,U,V;
vector<pii> a[maxn];
vector<int> b[maxn];
int d[5][maxn], tq[maxn], tu[maxn], tv[maxn], vst[maxn];

void dijkstra(int start, int cnt) {
    priority_queue<pii, vector<pii>, greater<pii> > qp;
    qp.push({0,start});
    for (int i = 1; i <= n; i++) d[cnt][i] = inf;
    d[cnt][start] = 0;
    while (qp.size()) {
        int u,val; tie(val,u) = qp.top(); qp.pop();
        if (d[cnt][u] < val) continue;
        for (pii tmp : a[u]) {
            int v,valv; tie(v,valv) = tmp;
            if (d[cnt][v] > valv + val) {
                d[cnt][v] = valv + val;
                qp.push({valv + val, v});
            }
        }
    }
}

void dfs(int u) {
    tu[u] = d[2][u];
    tv[u] = d[3][u];
    ans = min(ans, tu[u] + tv[u]);
    vst[u] = 1;
    for (int v : b[u]) {
        if (vst[v] == 0) dfs(v);
        tu[u] = min(tu[u], tu[v]);
        tv[u] = min(tv[u], tv[v]);
        ans = min({ ans, d[2][u] + tv[v], d[3][u] + tu[v] });
    }
//    cerr << u << " " << tu[u] << " " << tv[u] << endl;
}


signed main() {
//    freopen("BUS.INP", "r", stdin);
//    freopen("BUS.OUT", "w", stdout);
    cin.tie(0) -> sync_with_stdio(0);
    cin >> n >> m;
    cin >> S >> T >> U >> V;
    for (int i= 1; i <= m; i++) {
        int x,y,h; cin >> x >> y >> h;
        a[x].push_back({y,h});
        a[y].push_back({x,h});
    }
    dijkstra(S,0);
    dijkstra(T,1);
    dijkstra(U,2);
    dijkstra(V,3);

    D = d[0][T];
//    cerr << D << endl;
    for (int u = 1; u <= n; u++) {
        for (pii tmp : a[u]) {
            int v = tmp.first;
            if ( d[0][u] + tmp.second + d[1][v] == D ) {
                b[u].push_back(v);
//                cerr << u << " -> " << v << endl;
            }
        }
    }
    dfs(S);
    ans=min(ans,d[2][V]);
    cout << ans;
}

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