Submission #500093

#	Time	Username	Problem	Language	Result	Execution time	Memory
500093		aSSSd	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	334 ms	23128 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int rnd(int l,int r)
{
    return l+rng()%(r-l+1);
}
#define fasty ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define forinc(x,a,b) for(int x=a;x<=b;x++)
#define fordec(x,a,b) for(int x=a;x>=b;x--)
#define iii pair<ii,int>
#define fi first
#define se second
#define pb push_back
#define ll long long
#define ii pair<int,int>
#define mt make_tuple
#define getbit(x,i) ((x>>(i))&1)
#define batbit(x,i) (x|(1ll<<(i)))
#define tatbit(x,i) (x&~(1<<(i)))
#define endl '\n'
#define all(v) v.begin(), v.end()
#define gg exit(0);
#define int long long
const int N = 1e5 + 1000;
int n,m;
vector<ii> ke[N];
int s, t, u, v;
vector<int>  ditcha(int st)
{
    vector<int> d(n+1,1e16);
    priority_queue<ii, vector<ii>, greater<ii> > q;
    q.push({0, st});
    d[st] =0;
    while(!q.empty())
    {
        ii u = q.top();
        q.pop();
        if(u.fi != d[u.se]) continue;
        for(auto v : ke[u.se])
        {
            int cost = v.se;
            if(d[v.fi] > d[u.se] + v.se)
            {
                d[v.fi] = d[u.se] + v.se;
                q.push({d[v.fi], v.fi});
            }
        }
    }
    return  d;
}
int f[N], dp[N];
main()
{
   // freopen("task.inp" , "r" , stdin);
    fasty;
    cin >> n >> m;
    cin >> s >> t;
    cin >> u >> v;
    forinc(i,1,m)
    {
        int u, v, c;
        cin >> u >> v >>c;
        ke[u].pb({v,c});
        ke[v].pb({u,c});
    }
    vector<int> ds = ditcha(s);
    vector<int> dt = ditcha(t);
    vector<int> du = ditcha(u);
    vector<int> dv = ditcha(v);
    //cout << du[v] << "\n";
  //  cout << du[s] << "\n";
    int res = 1e18;
    for(int _ = 0 ; _ < 2 ; _++)
    {
        priority_queue<ii, vector<ii>, greater<ii> > q;
        forinc(i,0,n+1) dp[i] = 1e16;
        forinc(i,0,n+1) f[i] = 1e16;
        f[s]=0;
        dp[s] = du[s];
        //cout << dp[s] << " ";
        q.push({0,s});
        while(!q.empty())
        {
            ii u = q.top();
            q.pop();
            if(f[u.se] != u.fi) continue;
            //u - i
            //cout << dp[u.se] + dv[u.se] << "\n";
            //cout << u.se << " " << dp[u.se] << " " << dv[u.se] << "\n";
            //gg;
            res = min(res, dp[u.se] + dv[u.se]);
            //cout << res << " ";
           // s ----- u ------ v ----- t
            for(auto v : ke[u.se])
            {
                if(ds[v.fi] + dt[v.fi] == ds[t] )
                {
                    dp[v.fi] = min({dp[v.fi] , dp[u.se] , du[u.se]} );
                    if(f[v.fi] > v.se + f[u.se])
                    {
                        f[v.fi] = v.se + f[u.se];
                        q.push({f[v.fi], v.fi});
                    }
                }
            }
        }
        //cout << "co swap ko >> ";
        swap(du,dv);
    }
   // cout << res << "\n";
    res = min(res , du[v]);
    cout << res;

}

Compilation message (stderr)

commuter_pass.cpp: In function 'std::vector<long long int> ditcha(long long int)':
commuter_pass.cpp:42:17: warning: unused variable 'cost' [-Wunused-variable]
   42 |             int cost = v.se;
      |                 ^~~~
commuter_pass.cpp: At global scope:
commuter_pass.cpp:53:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   53 | main()
      | ^~~~

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