Submission #502691

#	Time	Username	Problem	Language	Result	Execution time	Memory
502691		XII	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	350 ms	18728 KiB

commuter_pass

/// https://oj.uz/problem/view/JOI18_commuter_pass
#include <bits/stdc++.h>
using namespace std;

using ll = long long;

#define fi first
#define se second
#define mp make_pair
#define eb emplace_back
#define ALL(x) (x).begin(), (x).end()

#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define FORU(i, a, b) for(int i = (a); i <= (b); ++i)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)

#define IOS cin.tie(0)->sync_with_stdio(false);
#define PROB "JOI18_commuter_pass"
void Fi(){
    if(fopen(PROB".inp", "r")){
        freopen(PROB".inp", "r", stdin);
        freopen(PROB".out", "w", stdout);
    }
}

const ll INF = 1e18;
const int N = 1e5 + 1;
bool vis[N];
int n, m;
int S, T, U, V;
using pi = pair<int, int>;
vector<pi> adj[N];

ll du[N], dv[N], ds[N];
ll dp[2][N], ans;

using pli = pair<ll, int>;
priority_queue<pli, vector<pli>, greater<pli>> pq;

void dijkstra1(const int &s, ll d[]){
    fill(d + 1, d + n + 1, INF);
    fill(vis + 1, vis + n + 1, false);
    pq.emplace(0, s); d[s] = 0;
    while(!pq.empty()){
        auto [wu, u] = pq.top(); pq.pop();
        if(wu != d[u] || vis[u]) continue;
        vis[u] = true;
        for(auto [wv, v]: adj[u]) if(!vis[v]){
            if(d[v] > wu + wv){
                d[v] = wu + wv;
                pq.emplace(d[v], v);
            }
        }
    }
}

void dijkstra2(const int &s, const int &t, ll d[]){
    fill(d + 1, d + n + 1, INF);
    fill(dp[0] + 1, dp[0] + n + 1, INF);
    fill(dp[1] + 1, dp[1] + n + 1, INF);
    fill(vis + 1, vis + n + 1, false);

    pq.emplace(0, s);
    d[s] = 0;
    dp[0][s] = du[s];
    dp[1][s] = dv[s];

    while(!pq.empty()){
        auto [wu, u] = pq.top(); pq.pop();
        if(wu != d[u] || vis[u]) continue;
        vis[u] = true;
        for(auto [wv, v]: adj[u]) if(!vis[v]){
            if(d[v] > wu + wv){
                dp[0][v] = min(du[v], dp[0][u]);
                dp[1][v] = min(dv[v], dp[1][u]);
                d[v] = wu + wv;
                pq.emplace(d[v], v);
            } else if(d[v] == wu + wv){
                if(min(du[v], dp[0][u]) + min(dv[v], dp[1][u]) < dp[0][v] + dp[1][v]){
                    dp[0][v] = min(du[v], dp[0][u]);
                    dp[1][v] = min(dv[v], dp[1][u]);
                }
            }
        }
    }
    ans = min(ans, dp[0][t] + dp[1][t]);
}

int main(){
    IOS;
    Fi();
    cin >> n >> m >> S >> T >> U >> V;
    FORU(i, 1, m){
        int u, v, w; cin >> u >> v >> w;
        adj[u].eb(w, v);
        adj[v].eb(w, u);
    }
    dijkstra1(U, du);
    dijkstra1(V, dv);
    ans = du[V];
    dijkstra2(S, T, ds);
    dijkstra2(T, S, ds);
    cout << ans;
    return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'void Fi()':
commuter_pass.cpp:21:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   21 |         freopen(PROB".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:22:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   22 |         freopen(PROB".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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