Submission #1266925

#	Time	Username	Problem	Language	Result	Execution time	Memory
1266925		VKhang	Commuter Pass (JOI18_commuter_pass)	C++20	100 / 100	208 ms	79400 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 5, MOD = 1e9 + 7;
const long long L = 1e18;
#define ll long long
#define fi first
#define se second
#define yes {cout << "YES";return;}
#define no  {cout << "NO"; return;}
#define pb push_back
#define MASK(i) (1ll << (i))
#define BIT(i, s) ((1ll << (i)) & (s))
#define all(a) a.begin(), a.end()
int n, m, s, t, u, v;
ll dist[N][4];
bool visited[N];
vector <pair <int, int>> adj[N];
int a[4];
priority_queue <pair <ll, int>, vector <pair <ll, int>>, greater <pair <ll, int>>> p;
bool minimize(ll &x, const ll y){
    if (x > y){
        x = y;
        return true;
    }
    return false;
}
void dijkstra(int id){
    memset(visited, false, sizeof visited);
    dist[a[id]][id] = 0;
    p.push({0, a[id]});
    while(p.size()){
        ll i = p.top().fi;
        int j = p.top().se;
        p.pop();
        if (visited[j]) continue;
        visited[j] = true;
        for (auto x: adj[j]){
            if (minimize(dist[x.fi][id], i + x.se)){
                p.push({dist[x.fi][id], x.fi});
            }
        }
    }
}
ll res;
ll ans = 1e18;
ll f[N][2];
void solve()
{
    cin >> n >> m >> s >> t >> u >> v;
    for (int i = 1; i <= m; i++){
        int x, y, w; cin >> x >> y >> w;
        adj[x].pb({y, w});
        adj[y].pb({x, w});
    }
    memset(dist, 0x3f, sizeof dist);
    a[0] = s; a[1] = t; a[2] = u; a[3] = v;
    dijkstra(0); dijkstra(1);
    dijkstra(2); dijkstra(3);
    res = dist[t][0];
    memset(f, 0x3f, sizeof f);
    memset(visited, false, sizeof visited);
    p.push({0, s});
    ans = dist[v][2];
    while(p.size()){
        ll i = p.top().fi;
        int j = p.top().se;
        p.pop();
        if (visited[j]) continue;
        visited[j] = true;
        f[j][0] = min(f[j][0], dist[j][2]);
        f[j][1] = min(f[j][1], dist[j][3]);
        ans = min(ans, f[j][0] + dist[j][3]);
        ans = min(ans, f[j][1] + dist[j][2]);
        for (auto x: adj[j]){
            if (i + x.se + dist[x.fi][1] == res){
                f[x.fi][0] = min(f[x.fi][0], f[j][0]);
                f[x.fi][1] = min(f[x.fi][1], f[j][1]);
                p.push({dist[x.fi][0], x.fi});
            }
        }
    }
    cout << ans;
}
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);cout.tie(NULL);
    if (fopen("VKhang.inp","r")){
        freopen("VKhang.inp","r",stdin);
        freopen("VKhang.out","w",stdout);
    }
    solve();
    return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:88:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   88 |         freopen("VKhang.inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:89:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   89 |         freopen("VKhang.out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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