제출 #876620

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
876620		Mr_Husanboy	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	193 ms	27340 KiB

commuter_pass

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



#ifdef LOCAL
#include "debugger.cpp"
#else
#define debug(...)
#endif
template<class T>
int len(T &a){
    return a.size();
}

using ll = long long;
using pii = pair<int,int>;
#define all(a) (a).begin(), (a).end()
#define ff first
#define ss second
string fileio = "";


mt19937 mt(time(nullptr));
const int mod = 1e9 + 7;
const int inf = 1e9;
const ll infl = 1e18;
const int maxn = 1e5 + 1;





void solve(){
    int n, m; cin >> n >> m;
    int s, t, a, b; cin >> s >> t >> a >> b;
    s --; t --; a --; b --;
    vector<vector<pair<int,int>>> g(n);
    vector<vector<int>> dag(n);

    for(int i = 0; i < m; i ++){
        int u, v, cost; cin >> u >> v >> cost;
        u --; v --;
        g[u].push_back({v, cost});
        g[v].push_back({u, cost});
    }

    priority_queue<pair<ll,int>> q;
    q.push({0, s});
    vector<ll> dis(n, infl);
    vector<bool> vis(n);
    dis[s] = 0;

    while(!q.empty()){
        int i = q.top().ss;
        q.pop();
        if(vis[i]) continue;
        vis[i] = 1;

        for(auto [u, cost] : g[i]){
            if(dis[u] < dis[i] + cost){
                continue;
            }
            if(dis[u] == dis[i] + cost){
                dag[u].push_back(i);
            }else{
                dis[u] = dis[i] + cost;
                dag[u] = {i};
                q.push({-dis[u], u});
            }
        }
    }

    debug(dag);

    vector<ll> da(n, infl), db(n, infl);

    da[a] = 0;
    q.push({0, a});
    vis.assign(n, false);
    while(!q.empty()){
        int i = q.top().ss;
        q.pop();
        if(vis[i]) continue;
        vis[i] = 1;
        for(auto [u, cost] : g[i]){
            if(da[u] > da[i] + cost){
                da[u] = da[i] + cost;
                q.push({-da[u], u});
            }
        }
    }

    db[b] = 0;
    q.push({0, b});
    vis.assign(n, false);
    while(!q.empty()){
        int i = q.top().ss;
        q.pop();
        if(vis[i]) continue;
        vis[i] = 1;
        for(auto [u, cost] : g[i]){
            if(db[u] > db[i] + cost){
                db[u] = db[i] + cost;
                q.push({-db[u], u});
            }
        }
    }
    vis.assign(n, 0);
    vector<ll> mna(n), mnb(n);
    ll ans = da[b];
    auto dfs = [&](auto &dfs, int i)->void{
        vis[i] = 1;
        debug(i);
        mna[i] = mnb[i] = infl;
        for(auto u : dag[i]){
            if(!vis[u]){ dfs(dfs, u); }
            mna[i] = min({mna[i], mna[u], da[u]});
            mnb[i] = min({mnb[i], mnb[u], db[u]});
        }
        ans = min({ans, da[i] + mnb[i], db[i] + mna[i]});
    };

    dfs(dfs, t);
    debug(mna);
    debug(mnb);

    cout << ans;
}

int main(){
    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
    auto start = chrono::high_resolution_clock::now();
    #ifndef LOCAL
    if(fileio.size()){
        freopen((fileio + ".in").c_str(), "r", stdin);
        freopen((fileio + ".out").c_str(), "w", stdout);
    }
    #endif
    int testcases = 1;
    #ifdef Tests
    cin >> testcases;
    #endif
    while(testcases --){
        solve();
        cout << '\n';
        #ifdef LOCAL
        cout << "_________________________" << endl;
        #endif
    }
    #ifdef LOCAL
    auto duration = chrono::duration_cast<chrono::microseconds>(chrono::high_resolution_clock::now() - start);
    
    cout << "time: " << (double)duration.count()/1000.0 << " milliseconds" << endl;
    #endif
    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:133:10: warning: variable 'start' set but not used [-Wunused-but-set-variable]
  133 |     auto start = chrono::high_resolution_clock::now();
      |          ^~~~~
commuter_pass.cpp:136:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  136 |         freopen((fileio + ".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:137:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  137 |         freopen((fileio + ".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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