Submission #957470

#	Time	Username	Problem	Language	Result	Execution time	Memory
957470		n3rm1n	Railway (BOI17_railway)	C++17	23 / 100	428 ms	524288 KiB

railway

#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
const int MAXN = 1e5 + 10, MAXLOG = 22;
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];
void dfs(int beg, int par, int depth)
{
    p[beg] = par;
    lvl[beg] = depth;
    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);
    }
}
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)
{
    int stu = u;
    int stv = v;
    if(lvl[u] > lvl[v])swap(u, v);
    int diff = lvl[v] - lvl[u];
    v = move_up(v, diff);
    //cout << "! " << stu << " " << stv << " "<< diff << endl;
    //cout << "newv " << v << endl;
    if(u == v)return u;
    int to = u;

    for (int i = MAXLOG - 1; i >= 0; -- i)
    {
        if(jump[u][i] != jump[v][i])
        {
            u = jump[u][i];
            v = jump[v][i];
        }
    }
    //cout << "for " << stu << ", " << stv << " is " << p[u] << endl;
    return p[u];
}
int s;
vector < int > que[MAXN];
vector < int /*colours*/ > endpoints[MAXN], startpoints[MAXN];
int cnt[MAXN];
int used[MAXN], active[MAXN];
int ans[MAXN];
bitset < MAXN > dfs2(int beg)
{
    used[beg] = 1;
    /// add

    int nb, id;
    bitset < MAXN > bs, vs;
    for (int i = 0; i < g[beg].size(); ++ i)
    {
        nb = g[beg][i].first;
        id = g[beg][i].second;

        if(!used[nb])
        {
            vs = dfs2(nb);
            bs = (bs | vs);
            ans[id] += vs.count();
        }
    }
    for (int i = 0; i < endpoints[beg].size(); ++ i)
    {
        bs[endpoints[beg][i]] = 1;
    }
    for (int i = 0; i < startpoints[beg].size(); ++ i)
    {
        bs[startpoints[beg][i]] = 0;
    }
    return bs;
}
void read_queries()
{
    int xx;
    for (int i = 1; i <= m; ++ i)
    {
        cin >> s >> xx;
        int lcaa = xx;
        que[i].push_back(xx);
        for (int j = 2; j <= s; ++ j)
        {
            cin >> xx;
            que[i].push_back(xx);
            lcaa = lca(lcaa, xx);
        }
        startpoints[lcaa].push_back(i);
       // cout << i << " lca is " << lcaa << endl;
        for (int j = 0; j < que[i].size(); ++ j)
        {

            endpoints[que[i][j]].push_back(i);
        }
    }

}
int main()
{
    speed();

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


    vector < int > anss;
    for (int i = 1; i <= n; ++ 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:31:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |     for (int i = 0; i < g[beg].size(); ++ i)
      |                     ~~^~~~~~~~~~~~~~~
railway.cpp: In function 'int lca(int, int)':
railway.cpp:57:9: warning: unused variable 'stu' [-Wunused-variable]
   57 |     int stu = u;
      |         ^~~
railway.cpp:58:9: warning: unused variable 'stv' [-Wunused-variable]
   58 |     int stv = v;
      |         ^~~
railway.cpp:65:9: warning: unused variable 'to' [-Wunused-variable]
   65 |     int to = u;
      |         ^~
railway.cpp: In function 'std::bitset<100010> dfs2(int)':
railway.cpp:91:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   91 |     for (int i = 0; i < g[beg].size(); ++ i)
      |                     ~~^~~~~~~~~~~~~~~
railway.cpp:103:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  103 |     for (int i = 0; i < endpoints[beg].size(); ++ i)
      |                     ~~^~~~~~~~~~~~~~~~~~~~~~~
railway.cpp:107:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  107 |     for (int i = 0; i < startpoints[beg].size(); ++ i)
      |                     ~~^~~~~~~~~~~~~~~~~~~~~~~~~
railway.cpp: In function 'void read_queries()':
railway.cpp:129:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  129 |         for (int j = 0; j < que[i].size(); ++ j)
      |                         ~~^~~~~~~~~~~~~~~
railway.cpp: In function 'int main()':
railway.cpp:155:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  155 |     for (int i = 0; i < anss.size(); ++ i)
      |                     ~~^~~~~~~~~~~~~

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