Submission #638765

#	Time	Username	Problem	Language	Result	Execution time	Memory
638765		Ez0zIOVgTsSgT	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	309 ms	23324 KiB

commuter_pass

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

void DBG() { cerr << "]\n"; }
template<class H, class... T> void DBG(H h, T... t) {
    cerr << h; if(sizeof...(t)) cerr << ", ";
    DBG(t...);
}
#ifdef LOCAL
#define dbg(...) cerr << "[" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#else
#define dbg(...) 0
#endif // LOCAL

#define FOR(i,a,b) for(int i = (a) ; i<(b) ; i++)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for(int i = (b)-1 ; i>=(a) ; i--)
#define R0F(i,a) ROF(i,0,a)
#define each(e,a) for(auto &e : (a))
#define sz(v) (int)(v).size()
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define pb push_back
#define tcT template<class T
#define nl "\n"
#define fi first
#define se second

using ll = long long;
using vi = vector<int>;
using pi = pair<int,int>;
using str = string;
tcT> using pqg = priority_queue<T,vector<T>,greater<T>>;

void setIO(string NAME = "") {
    cin.tie(0)->sync_with_stdio(0);
    if(sz(NAME)) {
        freopen((NAME + ".inp").c_str(),"r",stdin);
        freopen((NAME + ".out").c_str(),"w",stdout);
    }
}

tcT> bool ckmin(T&a, const T&b) {
    return b < a ? a=b,1 : 0; }
tcT> bool ckmax(T&a, const T&b) {
    return b > a ? a=b,1 : 0; }

const int MOD = 1e9 + 7;
const ll INF = 1e18;

const int MX = 1e5+5;
int N, M, S, T, U, V;
vector<pi> adj[MX];
ll distS[MX], distT[MX], distU[MX], distV[MX], dp[MX];

ll ans = INF;

void dijkstra(int src, ll dist[]) {
    FOR(i,1,N+1) dist[i] = INF;
    pqg<pair<ll,int>> pq;
    pq.push({dist[src] = 0, src});
    while(!pq.empty()) {
        int u = pq.top().se;
        ll du = pq.top().fi;
        pq.pop();
        if(du > dist[u]) continue;
        each(ed, adj[u]) {
            int v = ed.fi; ll dv = du + ed.se;
            if(ckmin(dist[v], dv)) pq.push({dist[v], v});
        }
    }
}

void dfs(int u, bool fromT) {
    if(~dp[u]) return;
    if(distS[u] + distT[u] != distS[T]) {
        dp[u] = INF;
        return;
    }
    dp[u] = distV[u];
    each(ed, adj[u]) {
        int v = ed.fi;
        if(fromT ? distT[u] + ed.se != distT[v] : distS[u] + ed.se != distS[v]) continue;
        dfs(v, fromT);
        ckmin(dp[u], dp[v]);
    }
    ckmin(ans, dp[u] + distU[u]);
}

void solve() {
    cin >> N >> M >> S >> T >> U >> V;
    F0R(i, M) {
        int u, v, w;
        cin >> u >> v >> w;
        adj[u].pb({v, w});
        adj[v].pb({u, w});
    }
    dijkstra(S, distS);
    dijkstra(T, distT);
    dijkstra(U, distU);
    dijkstra(V, distV);
    ans = distU[V];
    memset(dp, -1, sizeof dp);
    dfs(S, 0);
    memset(dp, -1, sizeof dp);
    dfs(T, 1);
    cout << ans << nl;
}

int main() {
    setIO();

    int t=1;
    //cin>>t;
    while(t-->0) {
        solve();
    }

    return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'void setIO(std::string)':
commuter_pass.cpp:38:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |         freopen((NAME + ".inp").c_str(),"r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:39:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   39 |         freopen((NAME + ".out").c_str(),"w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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