Submission #562775

#	Time	Username	Problem	Language	Result	Execution time	Memory
562775		Tien_Noob	Railway (BOI17_railway)	C++17	0 / 100	70 ms	22740 KiB

railway

//Make CSP great again
//Vengeance
#include <bits/stdc++.h>
#define TASK "TESTCODE"
#define Log2(x) 31 - __builtin_clz(x)
using namespace std;
const int N = 1e5, cbit = 16;
int dp[N + 1], tin[N + 1], tout[N + 1], timer, n, m, k, x[N], y[N], f[N + 1][cbit + 1], depth[N + 1];
vector<int> adj[N + 1], res, city;
void read()
{
    cin >> n >> m >> k;
    for (int i = 1; i < n; ++ i)
    {
        cin >> x[i] >> y[i];
        adj[x[i]].push_back(i);
        adj[y[i]].push_back(i);
    }
}
void preDFS(int u, int p)
{
    tin[u] = ++timer;
    for (int i : adj[u])
    {
        int v = x[i] ^ u ^ y[i];
        if (v == p)
        {
            continue;
        }
        depth[v] = depth[u] + 1;
        f[v][0] = u;
        for (int j = 1; j <= cbit; ++ j)
        {
            f[v][i] = f[f[v][j - 1]][j - 1];
        }
        preDFS(v, u);
    }
    tout[u] = ++timer;
}
int LCA(int u, int v)
{
    if (depth[u] > depth[v])
    {
        swap(u, v);
    }
    int x = depth[v] - depth[u];
    for (int i = cbit; i >= 0; -- i)
    {
        if ((x >> i) & 1)
        {
            v = f[v][i];
        }
    }
    if (u == v)
    {
        return u;
    }
    for (int i = cbit; i >= 0; -- i)
    {
        if (f[u][i] != f[v][i])
        {
            u = f[u][i];
            v = f[v][i];
        }
    }
    return f[u][0];
}
void ReadQuery()
{
    int s;
    cin >> s;
    city.clear();
    while(s--)
    {
        int u;
        cin >> u;
        city.push_back(u);
    }
    sort(city.begin(), city.end(), [&] (const int &u, const int &v)
    {
        return tin[u] < tin[v];
    });
    vector<int> t;
    for (int i = 1; i < city.size(); ++ i)
    {
        t.push_back(LCA(city[i], city[i - 1]));
    }
    move(t.begin(), t.end(), back_inserter(city));
    sort(city.begin(), city.end(), [&] (const int &u, const int &v)
    {
        return tin[u] < tin[v];
    });
    city.erase(unique(city.begin(), city.end()), city.end());
}
void DnC()
{
    stack<int> st;
    for (int v : city)
    {
        while(!st.empty())
        {
            int u = st.top();
            if (tin[v] <= tout[u])
            {
                --dp[u];
                ++dp[v];
                break;
            }
            else
            {
                st.pop();
            }
        }
        st.push(v);
    }
}
void DFS(int u, int p)
{
    for (int i : adj[u])
    {
        int v = x[i] ^ y[i] ^ u;
        if (v == p)
        {
            continue;
        }
        DFS(v, u);
        dp[u] += dp[v];
        if (dp[v] >= k)
        {
            res.push_back(i);
        }
    }
}
void solve()
{
    preDFS(1, 0);
    while(m--)
    {
        ReadQuery();
        DnC();
    }
    DFS(1, 0);
    sort(res.begin(), res.end());
    cout << res.size() << '\n';
    for (int i : res)
    {
        cout << i << ' ';
    }
}
int  main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    if (fopen(TASK".INP", "r"))
    {
        freopen(TASK".INP", "r", stdin);
        //freopen(TASK".OUT", "w", stdout);
    }
    int t = 1;
    bool typetest = false;
    if (typetest)
    {
        cin >> t;
    }
    for (int __ = 1; __ <= t; ++ __)
    {
        //cout << "Case " << __ << ": ";
        read();
        solve();
    }
}

Compilation message (stderr)

railway.cpp: In function 'void ReadQuery()':
railway.cpp:84:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   84 |     for (int i = 1; i < city.size(); ++ i)
      |                     ~~^~~~~~~~~~~~~
railway.cpp: In function 'int main()':
railway.cpp:156:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  156 |         freopen(TASK".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 8
• Subtask 2: 0 / 15
• Subtask 3: 0 / 7
• Subtask 4: 0 / 29
• Subtask 5: 0 / 16
• Subtask 6: 0 / 25