Submission #709940

#	Time	Username	Problem	Language	Result	Execution time	Memory
709940		noedit	Cities (BOI16_cities)	C++17	100 / 100	5021 ms	44384 KiB

cities

#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")

using namespace std;

const int INF = 1e9;
typedef long long ll;
const ll INFLL = 1e18;

const int MAXN = 2e5;
const int MAXK = 5;
const int MAXMSK = 32;
ll dp[MAXMSK][MAXN];
vector<vector<pair<int, int> > > g;

signed main()
{
    //ifstream cin("input.txt");
    //ofstream cout("output.txt");
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n, k, m;
    cin >> n >> k >> m;
    g.resize(n);
    vector<int> a(k);
    for (int i = 0; i < k; i++) cin >> a[i];
    for (int i = 0; i < m; i++)
    {
        int x, y, z;
        cin >> x >> y >> z;
        x--; y--;
        g[x].push_back({y, z});
        g[y].push_back({x, z});
    }
    for (int i = 0; i < MAXMSK; i++) for (int j = 0; j < n; j++) dp[i][j] = INFLL;
    for (int i = 0; i < k; i++)
    {
        dp[1 << i][a[i] - 1] = 0;
    }
    for (int mask = 1; mask < (1 << k); mask++)
    {
        for (int sub1 = mask; sub1; sub1 = (sub1 - 1) & mask)
        {
            int sub2 = mask ^ sub1;
            for (int v = 0; v < n; v++)
            dp[mask][v] = min(dp[mask][v], dp[sub1][v] + dp[sub2][v]);
        }
        set<pair<ll, int> > st;
        for (int v = 0; v < n; v++)
        {
            if (dp[mask][v] == INFLL) continue;
            st.insert({dp[mask][v], v});
        }
        while (!st.empty())
        {
            auto [d, v] = *st.begin();
            st.erase(st.begin());
            for (auto&[u, w] : g[v])
            {
                if (dp[mask][u] > d + w)
                {
                    st.erase({dp[mask][u], u});
                    dp[mask][u] = d + w;
                    st.insert({dp[mask][u], u});
                }
            }
        }
    }
    ll ans = INFLL;
//    for (int i = 0; i < (1 << k); i++){
//            cout << i << endl;
//        for (int j = 0; j < n; j++)
//        cout << dp[i][j] << " ";
//    cout << endl;
//    }
    for (int i = 0; i < n; i++)
    {
        ans = min(ans, dp[(1 << k) - 1][i]);
    }
    cout << ans;
    return 0;
}
/*
4 3 6
1 3 4
1 2 4
1 3 9
1 4 6
2 3 2
2 4 5
3 4 8
*/

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