Submission #1252218

#	Time	Username	Problem	Language	Result	Execution time	Memory
1252218		magic_trip	Cities (BOI16_cities)	C++20	52 / 100	871 ms	31544 KiB

cities

#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma optimize("unroll-loops")
#define fast ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define all(x) x.begin(), x.end()
#define rll(x) x.rbegin(), x.rend()
#define COMP(x) x.erase(unique(all(x)), x.end())
#define MOD 1000000007
#define MOD2 998244353
#define sz(x) (ll)x.size()
typedef __int128_t lll;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll,ll> pll;
typedef pair<ll, pll> PP;
const ll Lnf = 2e18;
ll n, k, m;
ll dist[5][101010];
ll dist2[5][5][101010];
vector<ll> imp;
vector<array<ll,2>> adj[101010];
bool chk[101010];
void get_dist(ll x, ll i){
    fill(dist[i],dist[i]+101010,Lnf);
    dist[i][x] = 0;
    priority_queue<array<ll,2>,vector<array<ll,2>>,greater<array<ll,2>>> pq;
    pq.push({0,x});
    while(sz(pq)){
        auto [d,cur] = pq.top(); pq.pop();
        if(d!=dist[i][cur])continue;
        for(auto [next,w] : adj[cur])if(dist[i][next] > d+w){
            dist[i][next] = d+w;
            pq.push({d+w,next});
        }
    }
}
void get_dist2(ll i, ll j){
    fill(dist2[i][j], dist2[i][j]+101010,Lnf);
    priority_queue<array<ll,2>,vector<array<ll,2>>,greater<array<ll,2>>> pq;
    for(int t = 1 ; t <= n ; t++){
        dist2[i][j][t] = dist[i][t] + dist[j][t];
        pq.push({dist2[i][j][t],t});
    }
    while(sz(pq)){
        auto [d,cur] = pq.top(); pq.pop();
        if(d!=dist2[i][j][cur])continue;
        for(auto [next,w] : adj[cur])if(dist2[i][j][next] > d+w){
            dist2[i][j][next] = d+w;
            pq.push({d+w,next});
        }
    }
}
int main(){
    fast;
    cin>>n>>k>>m;
    imp.resize(k);
    for(auto &i : imp)cin>>i, chk[i]=1;
    for(int i = 0 ; i < m ; i++){
        ll a,b,c; cin>>a>>b>>c; adj[a].push_back({b,c}); adj[b].push_back({a,c});
    }
    for(int i = 0 ; i < k ; i++)get_dist(imp[i],i);
    for(int i = 0 ; i < k ; i++)for(int j = i+1 ; j < k ; j++)get_dist2(i,j);
    ll ans = Lnf;
    for(int i = 1 ; i <= n ; i++)if(!chk[i]){
        ll s = 0;
        for(int j = 0 ; j < k ; j++)s+=dist[j][i];
        ans=min(ans,s);
    }
    for(int i = 0 ; i < k ; i++){
        ll s = 0;
        for(int j = 0 ; j < k ; j++)if(i!=j)s+=dist[j][imp[i]];
        ans=min(ans,s);
    }
    if(k<=3){
        cout<<ans;
        exit(0);
    }
    if(k==4){
        for(int u = 1 ; u <= n ; u++){
            for(int i = 0 ; i < (1<<k) ; i++)if(__builtin_popcount(i)==2){
                vector<ll> a, b;
                for(int j = 0 ; j < k ; j++){
                    if(i&(1<<j))a.push_back(j);
                    else b.push_back(j);
                }
                ans=min(ans,dist2[a[0]][a[1]][u] + dist2[b[0]][b[1]][u]);
            }
        }
        cout<<ans;
        exit(0);
    }
    for(int u = 1 ; u <= n ; u++){
        for(int i = 0 ; i < (1<<k) ; i++)if(__builtin_popcount(i)==2){
            vector<ll> a, b;
            for(int j = 0 ; j < k ; j++){
                if(i&(1<<j))a.push_back(j);
                else b.push_back(j);
            }
            ll s = dist2[a[0]][a[1]][u];
            for(int j = 0 ; j < (1<<k-2) ; j++)if(__builtin_popcount(j)==1){
                vector<ll> c,d;
                for(int x = 0 ; x < k-2 ; x++){
                    if(j&(1<<x))c.push_back(x);
                    else d.push_back(x);
                }
                ans = min(ans,s+dist[c[0]][u]+dist2[d[0]][d[1]][u]);
            }
        }
    }
    cout<<ans;
}

• Subtask 1: 0 / 22
• Subtask 2: 14 / 14
• Subtask 3: 15 / 15
• Subtask 4: 23 / 23
• Subtask 5: 0 / 26