Submission #1093537

#	Time	Username	Problem	Language	Result	Execution time	Memory
1093537		kustizus	Railway (BOI17_railway)	C++17	100 / 100	143 ms	64956 KiB

railway

// #pragma GCC optimize("O3","unroll-loops")
#include <bits/stdc++.h>
using namespace std;

// #define 
#define int long long
#define all(v) v.begin(), v.end()
#define fi first
#define se second
#define file "file"
#define bit(x, y) ((y >> x) & 1)
#define __lcm(a, b) a * b / __gcd(a, b)
#define R(x) {cout << x << "\n"; return;}
#define coutf(x) cout << fixed << setprecision(x) 
#define inter(a) cout << a << "\n"; fflush(stdout)

mt19937_64 rnd(chrono::high_resolution_clock::now().time_since_epoch().count());
// declare
const int N = 1e5;
int n, m, k, idx, in[N + 5], pre[N + 5], kk[N + 5];
vector <int> g[N + 5];
map <pair<int,int>,int> mp;

struct Lca_O1{
    vector <int> order;
    int h[N + 5], pos[N + 5], ST[20][2 * N + 5];
    void dfs(int i, int p)
    {
        in[i] = ++idx;
        order.push_back(i);
        pos[i] = order.size();
        for (int j : g[i])
            if (j != p)
            {
                h[j] = h[i] + 1;
                dfs(j, i);
                order.push_back(i);
            }
    }

    int P(int a, int b)
    {
        return h[a] < h[b] ? a : b;
    }

    void Build()
    {
        int sz = order.size();
        for (int i = 1; i <= sz; ++i) ST[0][i] = order[i - 1];
        for (int i = 1; i < 20; ++i)
            if ((1 << i) <= sz)
            {
                for (int j = 1; j <= sz - (1 << i) + 1; ++j)
                    ST[i][j] = P(ST[i - 1][j], ST[i - 1][j + (1 << (i - 1))]);
            }
    }

    int lca(int l, int r)
    {
        l = pos[l], r = pos[r];
        if (l > r) swap(l, r);
        int bit = __lg(r - l + 1);
        return P(ST[bit][l], ST[bit][r - (1 << bit) + 1]);
    }
    // declare h[1]
} lc;

void dfs(int i, int p)
{
    for (int j : g[i])
        if (j != p)
        {
            dfs(j, i);
            kk[j] = mp[{i, j}];
            pre[i] += pre[j];
        }
}

void Update(int u, int v)
{
    int p = lc.lca(u, v);
    ++pre[u];
    ++pre[v];
    pre[p] -= 2;
}

void Solve()
{
    cin >> n >> m >> k;
    for (int i = 1; i < n; ++i)
    {
        int u, v;
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
        mp[{u, v}] = mp[{v, u}] = i;
    }
    lc.dfs(1, 0);
    lc.Build();
    for (int i = 1; i <= m; ++i)
    {
        int d;
        cin >> d;
        vector <int> v;
        while (d--)
        {
            int x;
            cin >> x;
            v.push_back(x);
        }
        sort(all(v),[&](int a, int b)
        {
            return in[a] < in[b];
        });
        v.push_back(v[0]);
        for (int i = 1; i < v.size(); ++i)
            Update(v[i], v[i - 1]);
    }
    dfs(1, 0);
    vector <int> ans;
    for (int i = 2; i <= n; ++i)
        if (pre[i] / 2 >= k) ans.push_back(kk[i]);
    cout << ans.size() << "\n";
    sort(all(ans));
    for (int x : ans) cout << x << ' ';
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    if (fopen(file ".inp", "r"))
    {
        freopen (file ".inp", "r", stdin);
        freopen (file ".out", "w", stdout);
    }
    int t = 1;
    // cin >> t;
    while (t--) 
        Solve();
    cerr << "\nTIME: " << 1000 * clock() / CLOCKS_PER_SEC << "ms.";
}

Compilation message (stderr)

railway.cpp: In function 'void Solve()':
railway.cpp:116:27: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  116 |         for (int i = 1; i < v.size(); ++i)
      |                         ~~^~~~~~~~~~
railway.cpp: In function 'int main()':
railway.cpp:134:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  134 |         freopen (file ".inp", "r", stdin);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
railway.cpp:135:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  135 |         freopen (file ".out", "w", stdout);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 7 / 7
• Subtask 4: 29 / 29
• Subtask 5: 16 / 16
• Subtask 6: 25 / 25