Submission #1004211

#	Time	Username	Problem	Language	Result	Execution time	Memory
1004211		vjudge1	Railway (BOI17_railway)	C++17	0 / 100	1067 ms	417616 KiB

railway

#pragma GCC optimize("-O3")
#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#define ll long long
#define ld long double
#define vl vector<ll>
#define vi vector<int>
#define pii pair<int, int>
#define pll pair<ll, ll>
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define pb push_back
#define p_b pop_back
#define f first
#define s second
using namespace std;
using namespace __gnu_pbds;
typedef tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
const ll sz = 1e5+5;
vl g[sz];
set<ll>st[sz];
ll vis[sz], p[30][sz], lev[sz], par[sz];
void dfs(ll node)
{
    vis[node] = 1;
    for(auto u : g[node])
    {
        if(vis[u])
            continue;
        p[0][u] = node;
        par[u] = node;
        lev[u] = lev[node] + 1;
        dfs(u);
    }
}
ll jump(ll x, ll k)
{
    for(ll i = 0; i < 27; i++)
    {
        if((k >> i) & 1)
            x = p[i][x];
    }
    return x;
}
ll lca(ll x, ll y)
{
    if(lev[x] > lev[y])
        swap(x, y);
    ll d = lev[y] - lev[x];
    y = jump(y, d);
    if(x == y)
        return x;
    else
    {
        for(ll i = 26; i >= 0; i--)
        {
            if(p[i][x] != p[i][y])
            {
                x = p[i][x];
                y = p[i][y];
            }
        }
        return p[0][x];
    }
}
void solve()
{
    ll n, m, tk, i, j, l;
    cin >> n >> m >> tk;
    map<pll, ll>mp;
    for(ll i = 1; i <= n - 1; i++)
    {
        ll x, y;
        cin >> x >> y;
        g[x].pb(y);
        g[y].pb(x);
        mp[{x, y}] = i;
        mp[{y, x}] = i;
    }
    dfs(1);
    for(i = 1; i < 27; i++)
    {
        for(j = 1; j <= n; j++)
            p[i][j] = p[i-1][p[i-1][j]];
    }
    for(i = 1; i <= m; i++)
    {
        ll k;
        cin >> k;
        vl vect;
        vect.pb(0);
        for(j = 1; j <= k; j++){
            ll x;
            cin >> x;
            vect.pb(x);
        }
        for(j = 1; j <= k; j++){
            for(l = j + 1; l <= k; l++){
                ll a = lca(vect[j], vect[l]);
                ll x = vect[j], y = vect[l];
                while(x != a)
                {
                    st[mp[{x, par[x]}]].insert(i);
                    x = par[x];
                }
                while(y != a)
                {
                    st[mp[{y, par[y]}]].insert(i);
                    y = par[y];
                }
            }
        }
    }
    vl f;
    for(i = 1; i <= n - 1; i++)
    {
        if(st[i].size() >= tk)
            f.pb(i);
    }
    cout << f.size() << "\n";
    for(auto u : f)
        cout << u << ' ';
    cout << "\n";
}
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    ll tests = 1;
    //cin >> tests;
    while(tests--)
    {
        solve();
    }
}

Compilation message (stderr)

railway.cpp: In function 'void solve()':
railway.cpp:118:25: warning: comparison of integer expressions of different signedness: 'std::set<long long int>::size_type' {aka 'long unsigned int'} and 'long long int' [-Wsign-compare]
  118 |         if(st[i].size() >= tk)
      |            ~~~~~~~~~~~~~^~~~~

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