Submission #456395

#	Time	Username	Problem	Language	Result	Execution time	Memory
456395		Killer2501	Railway (BOI17_railway)	C++14	100 / 100	160 ms	39864 KiB

railway

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pll pair<ll, ll>
#define fi first
#define se second
#define pb push_back

const int N = 1e5+5;
const long long mod = 1e9+7;
const int base = 300;
ll m, n, k, a[N], ans, b[N], tong, d[N], c[N], lab[N], cnt, t, dp[N], h[N], P[N][20];
vector<pll> val[N];
vector<ll> adj[N], res;
ll pw(ll k, ll n)
{
    ll total = 1;
    for(; n; n >>= 1)
    {
        if(n & 1)total = total * k % mod;
        k = k * k % mod;
    }
    return total;
}
template<typename T>
void read(T&x)
{
    bool Neg=false;
    char c;
    for(c= getchar();c<'0'||c>'9';c=getchar())
        if(c=='-') Neg =!Neg;
    x = c-'0';
    for (c=getchar();c>='0'&&c<='9';c=getchar())
        x=x*10+c-'0';
    if(Neg&&x>0) x=-x;
}
ll findp(ll u)
{
    return lab[u] < 0 ? u : lab[u] = findp(lab[u]);
}
bool hop(ll u, ll v)
{
    u = findp(u);
    v = findp(v);
    if(u == v)return false;
    if(lab[u] > lab[v])swap(u, v);
    lab[u] += lab[v];
    lab[v] = u;
    return true;
}
string s;
void dfs(ll u, ll p)
{
   d[u] = ++t;
   for(ll i : adj[u])
   {
       ll v = a[i] + b[i] - u;
       if(v == p)continue;
       c[v] = i;
       P[v][0] = u;
       h[v] = h[u] + 1;
       for(int i = 1; i <= 18; i ++)P[v][i] = P[P[v][i-1]][i-1];
       dfs(v, u);
   }
}
void cal(ll u, ll p)
{
   for(ll i : adj[u])
   {
       ll v = a[i] + b[i] - u;
       if(v == p)continue;
       cal(v, u);
       dp[u] += dp[v];
   }
   //cout << u <<" "<<dp[u] << '\n';
}
ll lca(ll u, ll v)
{
    if(h[u] < h[v])swap(u, v);
    ll log = log2(h[u]);
    for(int i = log; i >= 0; i --)if(h[u] >= h[v] + (1<<i))u = P[u][i];
    if(u == v)return u;
    for(int i = log; i >= 0; i --)
    {
        if(P[u][i] && P[u][i] != P[v][i])
        {
            u = P[u][i];
            v = P[v][i];
        }
    }
    return P[u][0];
}
void sol()
{
    cin >> n >> m >> k;
    for(int i = 1; i < n; i ++)
    {
        cin >> a[i] >> b[i];
        adj[a[i]].pb(i);
        adj[b[i]].pb(i);
    }
    h[1] = 1;
    dfs(1, 0);
    while(m -- > 0)
    {
        cin >> t;
        vector<pll> kq;
        for(int i = 1; i <= t; i ++)
        {
            ll u;
            cin >> u;
            ++dp[u];
            kq.pb({d[u], u});

        }
        sort(kq.begin(), kq.end());
        for(int i = 0; i < t; i ++)
        {
            int j = (i+1)%t;
            --dp[lca(kq[i].se, kq[j].se)];
            //cout << kq[i].se <<" "<<kq[j].se << " "<<lca(kq[i].se, kq[j].se) << '\n';
        }
    }
    cal(1, 0);
    for(int i = 2; i <= n; i ++)if(dp[i] >= k)res.pb(c[i]);
    sort(res.begin(), res.end());
    cout << res.size() << '\n';
    for(ll x : res)cout << x <<" ";
}
int main()
{
    cin.tie(0);
    cout.tie(0);
    ios_base::sync_with_stdio(0);
    #define task "testss"
    if(fopen(task".inp", "r"))
    {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    int ntest = 1;
    //cin >> ntest;
    while(ntest -- > 0)
    sol();
}
/*
10 4
5 4 3 2 -1 0 0 0 0 0



*/

Compilation message (stderr)

railway.cpp: In function 'int main()':
railway.cpp:138:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  138 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
railway.cpp:139:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  139 |         freopen(task".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