Submission #1041387

#	Time	Username	Problem	Language	Result	Execution time	Memory
1041387		khanhtb	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	172 ms	49108 KiB

commuter_pass

#pragma GCC optimize("Ofast,unroll-loops")
#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define ld long double
#define pb push_back
#define pf push_front
#define vi vector<ll>
#define vii vector<vi>
#define pll pair<ll, ll>
#define vpll vector<pll>
#define all(a) a.begin(), a.end()
#define fi first
#define se second
using namespace std;
const ll mod = 1e9+7; 
const ll inf = 1e18;
const ll blocksz = 320;
const ll N = 3e5+8;
ll d[N][4];
int n,m,s,t,x,y;
vpll g[N];
bool use[N];
void dijkstra(int s, int t){
    for(int i = 1; i <= n; i++) d[i][t] = inf, use[i] = 0;
    priority_queue<pll,vpll,greater<pll>> pq;
    pq.push({0,s});
    d[s][t] = 0;
    while(pq.size()){
        int u = pq.top().se;
        ll dist = pq.top().fi;
        pq.pop();
        if(use[u]) continue;
        use[u] = 1;
        for(pll ed:g[u]){
            int v = ed.fi, w = ed.se;
            if(d[v][t] > d[u][t]+w){    
                d[v][t] = d[u][t]+w;
                pq.push({d[v][t],v});
            }
        }
    }
}
struct edge{
    ll u,v,w;
};
vector<edge> ed;
vector<int> adj[N];
vector<int> topo;
int vst[N];
void tps(int u){
    vst[u] = 1;
    for(int v:adj[u]){
        if(vst[v]) continue;
        tps(v);
    }
    topo.pb(u);
    vst[u] = 2;
}
ll dp[2][N];
void solve(){
    cin >> n >> m >> s >> t >> x >> y;
    for(int i = 1; i <= m; i++){
        int u,v,w;cin >> u >> v >> w;
        g[u].pb({v,w});
        g[v].pb({u,w});
        ed.pb({u,v,w});
    }
    dijkstra(s,0);
    dijkstra(t,1);
    dijkstra(x,2);
    dijkstra(y,3);
    for(edge e:ed){
        int u = e.u, v = e.v;
        ll w = e.w;
        if(d[u][0]+w+d[v][1] == d[t][0]) adj[u].pb(v);
        else if(d[v][0]+w+d[u][1] == d[t][0]) adj[v].pb(u);
    }
    tps(s);
    for(int i = 1; i <= n; i++) dp[0][i] = dp[1][i] = inf;
    for(int u:topo){
        dp[0][u] = d[u][2];
        dp[1][u] = d[u][3];
        for(int v:adj[u]){
            dp[0][u] = min(dp[0][u],dp[0][v]);
            dp[1][u] = min(dp[1][u],dp[1][v]);
        }
    }
    ll ans = d[y][2];
    for(int i = 1; i <= n; i++) ans = min({ans,dp[0][i]+d[i][3],dp[1][i]+d[i][2]});
    cout << ans;
}
signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    if (fopen("test.inp", "r")) {
        freopen("test.inp", "r", stdin);
        freopen("test.out", "w", stdout);
    }   
    ll T = 1;
    // cin >> T;
    for (ll i = 1; i <= T; i++) {
        solve();
        cout << '\n';
    }
}

Compilation message (stderr)

commuter_pass.cpp: In function 'void dijkstra(int, int)':
commuter_pass.cpp:31:12: warning: unused variable 'dist' [-Wunused-variable]
   31 |         ll dist = pq.top().fi;
      |            ^~~~
commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:98:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   98 |         freopen("test.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:99:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   99 |         freopen("test.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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