Submission #1245781

#	Time	Username	Problem	Language	Result	Execution time	Memory
1245781		vuxxcode	Cities (BOI16_cities)	C++20	14 / 100	462 ms	63228 KiB

cities

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define eb emplace_back
#define pb push_back
#define fi first
#define se second
#define ii pair<int,int>
#define pl pair<ll,ll>
#define ve vector
#define vi ve<int>
#define vvi ve<vi>
#define vl ve<ll>
#define vii ve<ii>
#define all(x) x.begin(), x.end()
#define fo(i,a,b) for (int i=(a),_b=(b); i<=_b; ++i)
#define fd(i,a,b) for (int i=(a),_b=(b); i>=_b; --i)
#define lc p+1
#define rc p+(mid-l+1)*2
#define maxi(a, b) a = max(a, b)
#define mini(a, b) a = min(a, b)
#define bit(s, i) (((s) >> (i)) & 1)
#define tup3 array<int,3>
#define tup4 array<int,4>
#define matrix vvi
#define cntBit(x) (__builtin_popcountll(x))
#define SZ(x) int(x.size())
#define x1 _
#define x2 __
#define y1 _
#define y2 __

const int N = 1e5+5, M = 1e6+5;
const int inf = 1e9+10;
const int mod = 1e9+7;
const int LG = 20, base=11111, B = 500;
bool st_mem;

int n, k, m;
ve<ii> g[N];
vl d[5];
ll cost[N][1<<6];

vl dij(int s) {
    vl d(n+1, 1e16);
    struct node {
        int u; ll d;
        bool operator < (const node &o) const {
            return d > o.d;
        }
    };
    priority_queue<node> q;
    d[s] = 0; q.push({s,0});
    while (q.size()) {
        node t = q.top(); q.pop();
        int u = t.u; ll dd = t.d;
        if (dd ^ d[u]) continue;
        for (auto &x:g[u]) {
            int v=x.fi, c=x.se;
            if (d[v]>dd+c) {
                d[v]=dd+c;
                q.push({v,dd+c});
            }
        }
    }
    return d;
}

void sol() {
    cin >> n >> k >> m;
    vi v(k);
    fo(i,0,k-1) cin >> v[i];
    fo(i,1,m) {
        int u, v, c; cin >> u >> v >> c;
        g[u].eb(v, c), g[v].eb(u, c);
    }
    fo(i,0,k-1) d[i]=dij(v[i]);
    if (k == 1) {
        cout << 0;
        return;
    }
    if (k == 2) {
        cout << d[0][v[1]];
        return;
    }
    ll ans=1e18;
    fo(i,1,n) {
        fo(j,1,(1<<k)-1)
            fo(l,0,k-1) if (j>>l&1)
                cost[i][j]+=d[l][i];
        mini(ans, cost[i][(1<<k)-1]);
    }
    fo(i,1,n) {
        fo(mask,1,(1<<k)-1) if (k-cntBit(mask)<=2) {
            vi s, t, tc = {i}, ot;
            ll sum=0;
            fo(j,0,k-1) {
                if (mask>>j&1) s.eb(j), tc.eb(v[j]), sum+=d[j][i];
                else t.eb(j), ot.eb(v[j]);
            }
            ll add=1e18;
            if (ot.empty()) add=0;
            for (int x:tc) if (t.size()) {
                ll cur=1e18;
                fo(_,1,2) {
                    ll tmp = d[t[0]][x];
                    if (ot.size()>1) tmp+=d[t[0]][ot[1]];
                    mini(cur, tmp);
                    if (ot.size()>1) {
                        swap(ot[0],ot[1]);
                        swap(t[0],t[1]);
                    }
                }
                mini(add,cur);
            }
            sum += add;
            mini(ans, sum);
        }
    }
    cout << ans;
}

bool en_mem;
signed main() {
    ios::sync_with_stdio(0); cin.tie(0);
    if(fopen("A.inp","r")) {
        freopen("A.inp","r",stdin);
        freopen("A.out","w",stdout);
    }
    int tc = 1; // cin >> tc;
    fo(i,1,tc) sol();
     // cerr << abs(&en_mem - &st_mem) / 1024.0 / 1024.0;
    return 0;
}

Compilation message (stderr)

cities.cpp: In function 'int main()':
cities.cpp:127:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  127 |         freopen("A.inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~
cities.cpp:128:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  128 |         freopen("A.out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~

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