Submission #1087585

#	Time	Username	Problem	Language	Result	Execution time	Memory
1087585		pqthangv	Commuter Pass (JOI18_commuter_pass)	C++11	31 / 100	245 ms	37288 KiB

commuter_pass

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

#define fi first
#define se second
#define gcd __gcd
#define siz(v) v.size()
#define pb push_back
#define pi pair<int,int>
#define all(v) (v).begin(), (v).end()
#define FOR(i, a, b) for(int i = (a); i <= (b); i++)
///#define int long long

using ll = long long;
using ld = long double;
using ull = unsigned long long;

template<typename T> bool ckmx(T &a, T b){if(a < b) return a = b, true; return false;}
template<typename T> bool ckmn(T &a, T b){if(a > b) return a = b, true; return false;}

const int N = 2e5+5;
const ll MOD = 1e9+7;
const ll INF = 1e18;


struct Edge{
    int u,v; ll w;
};

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

void Dijkstra(int id, int source)
{
    priority_queue<pair<ll, int>> pq;
    for(int i = 1; i <= n; i++){
        d[id][i] = (i == source ? 0 : INF);
    }
    pq.push(make_pair(0, source));

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

        if(e.fi > d[id][e.se]) continue;

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

void get_topoOrder(int x){
    vis[x] = true;
    for(int v : adj[x]){
        if(!vis[v]) get_topoOrder(v);
    }
    dp[0][x] = dp[1][x] = INF;
    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,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(0, S);
    Dijkstra(1, T);
    Dijkstra(2, X);
    Dijkstra(3, Y);

    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[0][T] == d[1][u] + E[i].w + d[0][v]){
            adj[u].push_back(v);
            adj[v].push_back(u);
        }
    }

    for(int i = 1; i <= n; i++){
        sort(adj[i].begin(), adj[i].end());
        adj[i].erase(unique(adj[i].begin(), adj[i].end()), adj[i].end());
    }

    get_topoOrder(S);

    reverse(topo.begin(), topo.end());

    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]);
        answer = min(answer, dp[0][v] + dp[1][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]);
        }
    }

    cout << answer <<"\n";
}

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

    #define name "InvMOD"
    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:127:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  127 |         freopen(name".INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:128:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  128 |         freopen(name".OUT","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

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