Submission #875195

#	Time	Username	Problem	Language	Result	Execution time	Memory
875195		trytovoi	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	233 ms	28464 KiB

commuter_pass

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

template<typename T> bool ckmin(T& x, const T& y) { return x > y ? x = y, 1 : 0; }
template<typename T> bool ckmax(T& x, const T& y) { return x < y ? x = y, 1 : 0; }

const long long INF = (long long) 1e18;
const int MAX_NODE = (int) 1e5 + 5;
const int MAX_EDGE = (int) 2e5 + 5;

int n, m;
int S, T, U, V;
vector<pair<int, int>> adj[MAX_NODE];

struct Data {
    int u;
    long long w;
    
    Data(int _u = 0, long long _w = 0) {
        u = _u; w = _w;
    }
    
    bool operator < (const Data& other) const {
        return w > other.w;
    }
};

void dijkstra(int s, vector<long long>& dist) {
    priority_queue<Data> Q;
    Q.push(Data(s, dist[s] = 0));
    while (!Q.empty()) {
        auto [u, du] = Q.top(); Q.pop();
        if (du != dist[u]) continue;
        
        for (auto [v, dv] : adj[u]) {
            long long cost = du + dv;
            if (ckmin(dist[v], cost)) Q.push(Data(v, dist[v]));
        }
    }
}

namespace SUBTASK_1 {
    
    void solve(void) {
        vector<long long> distSU(n + 1, INF);
        dijkstra(S, distSU);
        vector<long long> distT(n + 1, INF);
        dijkstra(T, distT);
        vector<long long> distV(n + 1, INF);
        dijkstra(V, distV);
        
        long long ans = distV[U];
        for (int i = 1; i <= n; ++i) if (distSU[i] + distT[i] == distSU[T]) ckmin(ans, distV[i]);
        cout << ans << '\n';
    }
    
}

namespace SUBTASK_3 {
    
    const int MX = 303;
    
    long long dist[MX][MX];
    
    void solve(void) {
        memset(dist, 0x3f, sizeof dist);
        for (int i = 1; i <= n; ++i) {
            dist[i][i] = 0;
            for (auto [v, w] : adj[i]) dist[i][v] = dist[v][i] = w;
        }
        
        for (int k = 1; k <= n; ++k) for (int i = 1; i <= n; ++i) for (int j = 1; j <= n; ++j)
            ckmin(dist[i][j], dist[i][k] + dist[k][j]);
        
        long long ans = dist[U][V];
        for (int i = 1; i <= n; ++i) for (int j = 1; j <= n; ++j) 
            if (dist[S][i] + dist[i][j] + dist[j][T] == dist[S][T]) ckmin(ans, min(dist[V][i] + dist[j][U], dist[U][i] + dist[j][V]));
        cout << ans << '\n';
    }
    
}

namespace FULL {

vector<int> tree[MAX_NODE];

void solve(void) {
    vector<long long> distS(n + 1, INF), distT(n + 1, INF), distU(n + 1, INF), distV(n + 1, INF);
    dijkstra(S, distS); dijkstra(T, distT); dijkstra(U, distU); dijkstra(V, distV);
    for (int u = 1; u <= n; ++u) for (auto [v, w] : adj[u]) {
        if (distS[u] + w + distT[v] == distS[T]) tree[u].push_back(v);
    }
    long long ans = distU[V];
    vector<vector<long long>> dp(n + 1, vector<long long>(2, INF));
    vector<bool> vis(n + 1, false);
    function<void(int)> dfs = [&](int u) {
        vis[u] = true;
        for (int v : tree[u]) {
            if (!vis[v]) dfs(v);
            ckmin(dp[u][0], min(dp[v][0], distU[v]));
            ckmin(dp[u][1], min(dp[v][1], distV[v]));
        }
        if (dp[u][0] < INF) ckmin(ans, dp[u][0] + distV[u]);
        if (dp[u][1] < INF) ckmin(ans, dp[u][1] + distU[u]);
    }; 
    dfs(S);
    cout << ans << '\n';
}
    
}

int main(void) {
    ios::sync_with_stdio(false); cin.tie(0);
    cin >> n >> m >> S >> T >> U >> V;
    for (int i = 1; i <= m; ++i) {
        int u, v, w; cin >> u >> v >> w;
        adj[u].push_back(make_pair(v, w));
        adj[v].push_back(make_pair(u, w));
    }
    if (S == U) {
        SUBTASK_1::solve();
        return 0;
    }
    if (n <= 300) {
        SUBTASK_3::solve();
        return 0;
    }
    FULL::solve();
    return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'void dijkstra(int, std::vector<long long int>&)':
commuter_pass.cpp:32:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   32 |         auto [u, du] = Q.top(); Q.pop();
      |              ^
commuter_pass.cpp:35:19: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   35 |         for (auto [v, dv] : adj[u]) {
      |                   ^
commuter_pass.cpp: In function 'void SUBTASK_3::solve()':
commuter_pass.cpp:69:23: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   69 |             for (auto [v, w] : adj[i]) dist[i][v] = dist[v][i] = w;
      |                       ^
commuter_pass.cpp: In function 'void FULL::solve()':
commuter_pass.cpp:90:44: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   90 |     for (int u = 1; u <= n; ++u) for (auto [v, w] : adj[u]) {
      |                                            ^

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