Submission #399450

#	Time	Username	Problem	Language	Result	Execution time	Memory
399450		SavicS	Commuter Pass (JOI18_commuter_pass)	C++14	0 / 100	129 ms	18008 KiB

commuter_pass

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <bits/stdc++.h>

#define fi first
#define se second
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define ff(i,a,b) for(int i=a;i<=b;i++)
#define fb(i,b,a) for(int i=b;i>=a;i--)

using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef pair<ll,int> pii;
const int maxn = 100005;
const ll inf = 1e18 + 5;

template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

// os.order_of_key(k) the number of elements in the os less than k
// *os.find_by_order(k)  print the k-th smallest number in os(0-based)

int n, m;
int S, T;
int A, B;

vector<pii> g[maxn];

// shortest path DAG graph za S do T
ll distS[maxn];
ll distT[maxn];
ll distA[maxn];
ll distB[maxn];
void dij(int s, ll dist[]) {
    ff(i,1,n)dist[i] = inf;
    priority_queue<pii, vector<pii>, greater<pii>> pq;

    pq.push({dist[s] = 0, s});
    while(!pq.empty()) {
        pii v = pq.top();
        pq.pop();
        if(dist[v.se] < v.fi)return;
        for(auto c : g[v.se]) {
            int u = c.fi;
            int w = c.se;
            if(dist[u] > w + v.fi) {
                pq.push({dist[u] = w + v.fi, u});
            }
        }
    }

}

ll rez = inf;
ll mn1[maxn];
ll mn2[maxn];

bool visited[maxn];
void dfs1(int v) {
    visited[v] = 1;

    mn1[v] = min(mn1[v], distB[v]);
    mn2[v] = min(mn2[v], distA[v]);

    rez = min(rez, mn1[v] + distA[v]);
    rez = min(rez, mn2[v] + distB[v]);
//
//	cout << "v: " << v << endl;
//	cout << "mn: " << mn2[v] << endl;
//	cout << endl;

    for(auto c : g[v]) {
        int u = c.fi;
        int w = c.se;
        if(visited[u])continue;
        if(distS[v] + w + distT[u] == distS[T]) {
            // onda je na shortest path (odnosno DAG)

            mn1[u] = min(mn1[u], mn1[v]);
            mn2[u] = min(mn2[u], mn2[v]);
            dfs1(u);
        }
    }
}

void dfs2(int v) {
    visited[v] = 1;

    mn1[v] = min(mn1[v], distB[v]);
    mn2[v] = min(mn2[v], distA[v]);

    rez = min(rez, mn1[v] + distA[v]);
    rez = min(rez, mn2[v] + distB[v]);

//	cout << "v: " << v << endl;
//	cout << "mn: " << mn2[v] << endl;
//	cout << endl;

    for(auto c : g[v]) {
        int u = c.fi;
        int w = c.se;
        if(visited[u])continue;
        if(distT[v] + w + distS[u] == distT[S]) {
            // onda je na shortest path (odnosno DAG)
            mn1[u] = min(mn1[u], mn1[v]);
            mn2[u] = min(mn2[u], mn2[v]);
            dfs2(u);
        }
    }
}

int main() 
{
    ios::sync_with_stdio(false);
    cout.tie(nullptr);
    cin.tie(nullptr);
    cin >> n >> m >> S >> T >> A >> B;
    ff(i,1,m) {
        int u, v, w;
        cin >> u >> v >> w;
        g[u].pb({v, w});
        g[v].pb({u, w});
    }

    dij(S, distS);
    dij(T, distT);
    dij(A, distA);
    dij(B, distB);
    rez = distB[A];

    ff(i,1,n)mn1[i] = inf, mn2[i] = inf;
    dfs1(S);

    ff(i,1,n)mn1[i] = inf, mn2[i] = inf;
    memset(visited, 0, sizeof(visited));
    dfs2(T);

    cout << rez << endl;

    return 0;
}
/**



// probati bojenje sahovski ili slicno

**/

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