Submission #1087604

#	Time	Username	Problem	Language	Result	Execution time	Memory
1087604		shiori_chan	Commuter Pass (JOI18_commuter_pass)	C++14	31 / 100	231 ms	42924 KiB

commuter_pass

#include<bits/stdc++.h>


#define fi first
#define se second

using namespace std;

using ll = long long;

const int N = 4e5+5;
const ll inf = 1e15;

struct Edge{
    int u,v; ll w;
};
int n, m, X, Y, S, T;
ll d[4][N], dp[2][N];
bool vis[N];
vector<int> adj[N], topo;
vector<pair<int,ll>> g[N];
Edge E[N];

void Dijkstra(int source, int type)
{
    priority_queue<pair<ll,int>> pq;

    for(int i = 1; i <= n; i++){
        d[type][i] = inf;
    }
    d[type][source] = 0;
    pq.push({0, source});

    while(!pq.empty()){
        pair<ll,int> t = pq.top(); pq.pop();

        if(t.fi > d[type][t.se]) continue;

        int x = t.se;
        for(pair<int,ll> e : g[x]){
            int v = e.fi; ll w = e.se;
            if(d[type][v] > d[type][x] + w){
                d[type][v] = d[type][x] + w;
                pq.push({-d[type][v], v});
            }
        }
    }
    return;
}

void get_topoOrder(int x){
    vis[x] = true;
    dp[0][x] = inf;
    dp[1][x] = inf;
    for(int v : adj[x]){
        if(vis[v]) continue;
        get_topoOrder(v);
    }
    topo.push_back(x);
    return;
}

void solve()
{
    cin >> n >> m;
    cin >> S >> T >> X >> Y;
    for(int i = 1; i <= m; i++){
        int u,v; ll w; cin >> u >> v >> w;
        g[u].push_back(make_pair(v, w));
        g[v].push_back(make_pair(u, w));
        E[i] = {u, v, w};
    }

    Dijkstra(S, 0);
    Dijkstra(T, 1);
    Dijkstra(X, 2);
    Dijkstra(Y, 3);

    for(int i = 1; i <= m; i++){
        int u = E[i].u, v = E[i].v;
        if(d[0][u] + E[i].w + d[1][v] == d[0][T] || d[1][u] + E[i].w + d[0][v] == d[0][T]){
            adj[u].push_back(v);
            adj[v].push_back(u);
        }
    }

    get_topoOrder(S);
    ll answer = d[2][Y];


    for(int v : topo){
        dp[0][v] = min(dp[0][v], d[2][v]);
        dp[1][v] = min(dp[1][v], d[3][v]);
        for(int x : adj[v]){
            dp[0][x] = min(dp[0][x], dp[0][v]);
            dp[1][x] = min(dp[1][x], dp[1][v]);
        }
        answer = min(answer, dp[0][v] + dp[1][v]);
    }
    cout << answer <<"\n";
}

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

    #define name "task"
    if(fopen(name".INP", "r")){
        freopen(name".INP", "r", stdin);
        freopen(name".OUT", "w", stdout);
    }

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

Compilation message (stderr)

commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:110:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  110 |         freopen(name".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:111:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  111 |         freopen(name".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 16 / 16
• Subtask 2: 15 / 15
• Subtask 3: 0 / 24
• Subtask 4: 0 / 45