Submission #957836

#	Time	Username	Problem	Language	Result	Execution time	Memory
957836		n3rm1n	Railway (BOI17_railway)	C++17	36 / 100	56 ms	27404 KiB

railway

#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
const int MAXN = 1e5 + 1, MAXM = 5e4+10, MAXLOG = 21;
void speed()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
}
int n, m, k;
vector < pair < int, int > > g[MAXN];
void read_graph()
{
    cin >> n >> m >> k;
    int from, to;
    for (int i = 1; i < n; ++ i)
    {
        cin >> from >> to;
        g[from].push_back({to, i});
        g[to].push_back({from, i});
    }
}

int p[MAXN], lvl[MAXN], tin[MAXN], tout[MAXN];
int tt = 0;
void dfs(int beg, int par, int depth)
{
    tt ++;
    p[beg] = par;
    lvl[beg] = depth;
    tin[beg] = tt;
    int nb;
    for (int i = 0; i < g[beg].size(); ++ i)
    {
        nb = g[beg][i].first;
        if(lvl[nb] == 0)
        {
            dfs(nb, beg, depth+1);
            tout[beg] = max(tout[beg], tout[nb] + 1);
        }
    }
}
int jump[MAXN][MAXLOG];
void fill_jump()
{
    for (int i = 1; i <= n; ++ i)
        jump[i][0] = p[i];
    for (int j = 1; j < MAXLOG; ++ j)
        for (int i = 1; i <= n; ++ i)
            jump[i][j] = jump[jump[i][j-1]][j-1];
}
int move_up(int v, int dist)
{
    for (int i = 0; (1 << i) <= dist; ++ i)
    {
        if((1 << i) & dist)
            v = jump[v][i];
    }
    return v;
}
int lca(int u, int v)
{
    if(lvl[u] > lvl[v])swap(u, v);
    int diff = lvl[v] - lvl[u];
    v = move_up(v, diff);
    if(u == v)return u;
    for (int i = MAXLOG - 1; i >= 0; -- i)
    {
        if(jump[u][i] != jump[v][i])
        {
            u = jump[u][i];
            v = jump[v][i];
        }
    }
    return p[u];
}
int s;
bool cmp(int x, int y)
{
    return (tout[x] < tout[y]);
}
int cnt[MAXN];
int ans[MAXN];
int dfs2(int beg, int par)
{
    int take_up = cnt[beg];
    int nb, id;
    int from_down;
    for (int i = 0; i < g[beg].size(); ++ i)
    {
        nb = g[beg][i].first;
        id = g[beg][i].second;

        if(nb != par)
        {
            from_down = dfs2(nb, beg);
            take_up += from_down;
            ans[id] += from_down;
        }
    }

    return take_up;
}
void read_queries()
{
    int xx, lcaa;
    vector < int > que;
    for (int i = 1; i <= m; ++ i)
    {
        cin >> s >> xx;
        que.clear();
        que.push_back(xx);
        for (int j = 2; j <= s; ++ j)
        {
            cin >> xx;
            que.push_back(xx);

        }
        sort(que.begin(), que.end(), cmp);
        lcaa = que[0];
        for (int j = 1; j < que.size(); ++ j)
        {
            xx = que[j];
            cnt[lcaa] ++;
            cnt[xx] ++;
            lcaa = lca(lcaa, xx);
            cnt[lcaa] -= 2;
        }
    }

}
int main()
{
    speed();

    read_graph();
    dfs(1, 0, 1);
    fill_jump();
    read_queries();
    dfs2(1, 0);


    vector < int > anss;
    for (int i = 1; i <= n; ++ i)
    {
       // cout << ans[i] << " ";
        if(ans[i] >= k)anss.push_back(i);
    }

    cout << anss.size() << endl;
    for (int i = 0; i < anss.size(); ++ i)
        cout << anss[i] << " ";
    cout << endl;
    return 0;
}

Compilation message (stderr)

railway.cpp: In function 'void dfs(int, int, int)':
railway.cpp:34:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   34 |     for (int i = 0; i < g[beg].size(); ++ i)
      |                     ~~^~~~~~~~~~~~~~~
railway.cpp: In function 'int dfs2(int, int)':
railway.cpp:90:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   90 |     for (int i = 0; i < g[beg].size(); ++ i)
      |                     ~~^~~~~~~~~~~~~~~
railway.cpp: In function 'void read_queries()':
railway.cpp:122:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  122 |         for (int j = 1; j < que.size(); ++ j)
      |                         ~~^~~~~~~~~~~~
railway.cpp: In function 'int main()':
railway.cpp:152:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  152 |     for (int i = 0; i < anss.size(); ++ i)
      |                     ~~^~~~~~~~~~~~~

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