Submission #1004450

#	Time	Username	Problem	Language	Result	Execution time	Memory
1004450		vjudge1	Railway (BOI17_railway)	C++17	29 / 100	1031 ms	41412 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], q[sz];
ll vis[sz], lev[sz], p[30][sz], dist[sz], par[sz];
void dfs(ll node)
{
    vis[node] = 1;
    for(auto u : g[node])
    {
        if(vis[u])
            continue;
        p[0][u] = node;
        lev[u] = lev[node] + 1;
        par[u] = node;
        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 y;
    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 dfs2(ll node)
{
    vis[node] = 1;
    for(auto u : g[node])
    {
        if(vis[u])
            continue;
        dfs2(u);
        dist[node] += dist[u];
    }
}
void dfs3(ll node, ll d)
{
    vis[node] = 1;
    for(auto u : g[node])
    {
        if(vis[u])
            continue;
        dfs3(u, d);
        dist[node] += dist[u];
    }
    dist[node] = min(dist[node], d);
}
void solve()
{
    ll n, m, k, i, j, l;
    cin >> n >> m >> k;
    vector<pll>vect;
    for(i = 1; i <= n - 1; i++)
    {
        ll x, y;
        cin >> x >> y;
        g[x].pb(y);
        g[y].pb(x);
        vect.pb({x, y});
    }
    dfs(1);
    for(i = 1; i < 27; i++)
    {
        for(j = 1; j <= n; j++)
            p[i][j] = p[i-1][p[i-1][j]];
    }
    ll cnt = 0;
    for(i = 1; i <= m; i++)
    {
        ll s;
        cin >> s;
        if(s == 2)
            cnt++;
        for(j = 1; j <= s; j++)
        {
            ll x;
            cin >> x;
            q[i].pb(x);
        }
    }
    if(cnt == m)
    {
        for(i = 1; i <= m; i++)
        {
            ll x = q[i][0], y = q[i][1];
            ll a = lca(x, y);
            dist[x]++;
            dist[y]++;
            dist[a]--;
            dist[par[a]] -= 2;
        }
        for(i = 1; i <= n; i++)
            vis[i] = 0;
        dfs2(1);
        vl f;
        for(i = 0; i < vect.size(); i++)
        {
            ll x = vect[i].f, y = vect[i].s;
            if(min(dist[x], dist[y]) >= k)
                f.pb(i+1);
        }
        cout << f.size() << "\n";
        for(auto u : f)
            cout << u << ' ';
        cout << "\n";
    }
    else
    {
        for(i = 1; i <= m; i++)
        {
            for(j = 0; j < q[i].size(); j++)
            {
                for(l = j + 1; l < q[i].size(); l++)
                {
                    ll x = q[i][j], y = q[i][l];
                    ll a = lca(x, y);
                    dist[x]++;
                    dist[y]++;
                    dist[a]--;
                    dist[par[a]] -= 2;
                }
            }
            for(j = 1; j <= n; j++)
                vis[j] = 0;
            dfs3(1, i);
        }
        vl f;
        for(i = 0; i < vect.size(); i++)
        {
            ll x = vect[i].f, y = vect[i].s;
            if(min(dist[x], dist[y]) >= k)
                f.pb(i+1);
        }
        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:137:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  137 |         for(i = 0; i < vect.size(); i++)
      |                    ~~^~~~~~~~~~~~~
railway.cpp:152:26: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  152 |             for(j = 0; j < q[i].size(); j++)
      |                        ~~^~~~~~~~~~~~~
railway.cpp:154:34: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  154 |                 for(l = j + 1; l < q[i].size(); l++)
      |                                ~~^~~~~~~~~~~~~
railway.cpp:169:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  169 |         for(i = 0; i < vect.size(); i++)
      |                    ~~^~~~~~~~~~~~~

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