Submission #1182646

#	Time	Username	Problem	Language	Result	Execution time	Memory
1182646		jerzyk	Cat Exercise (JOI23_ho_t4)	C++20	100 / 100	216 ms	62124 KiB

Main

#include <bits/stdc++.h>

using namespace std;
#define pb push_back
#define st first
#define nd second
typedef long long ll;
typedef long double ld;
const ll I = 1000'000'000'000'000'000LL;
const int II = 2'000'000'000;
const ll M = 1000'000'007LL;
const int N = 1000'007;
int fau[N];
ll ans[N];
int per[N];
vector<int> ed[N];

int wys[N];
int jp[N][20];

int Find(int v)
{
    if(fau[v] == v) return v;
    return (fau[v] = Find(fau[v]));
}

void Union(int a, int b)
{
    fau[Find(b)] = Find(a);
}

void DFS(int v)
{
    for(int i = 1; i <= 19; ++i)
        jp[v][i] = jp[jp[v][i - 1]][i - 1];
    for(int i = 0; i < (int)ed[v].size(); ++i)
    {
        if(wys[ed[v][i]]) continue;
        wys[ed[v][i]] = wys[v] + 1;
        jp[ed[v][i]][0] = v;
        DFS(ed[v][i]);
    }
}

int Dis(int a, int b)
{
    int ans = 0;
    if(wys[a] < wys[b]) swap(a, b);
    for(int i = 19; i >= 0; --i)
        if(wys[jp[a][i]] >= wys[b])
            {a = jp[a][i]; ans += (1<<i);}
    for(int i = 19; i >= 0; --i)
        if(jp[a][i] != jp[b][i])
        {
            a = jp[a][i]; b = jp[b][i];
            ans += 2 * (1<<i);
        }
    if(a == b) return ans;
    return ans + 2;
}

void Solve()
{
    int n, a, b;
    cin >> n;
    for(int i = 1; i <= n; ++i)
        cin >> per[i];
    for(int i = 1; i < n; ++i)
    {
        cin >> a >> b; a = per[a]; b = per[b];
        ed[a].pb(b); ed[b].pb(a);
    }
    wys[1] = 1;
    DFS(1);
    for(int v = 1; v <= n; ++v)
    {
        int ne;
        fau[v] = v;
        //cout << v << ":\n";
        for(int j = 0; j < (int)ed[v].size(); ++j)
        {
            if(ed[v][j] > v) continue;
            ne = Find(ed[v][j]);
            //cout << "E: " << ed[v][j] << " " << ne << " " << Dis(ne, v) << "\n";
            ans[v] = max(ans[v], ans[ne] + Dis(ne, v));
            Union(v, ne);
        }
    }
    cout << ans[n] << "\n";
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    //int t; cin >> t;
    //while(t--)
        Solve();

    return 0;
}

• Subtask 1: 7 / 7
• Subtask 2: 7 / 7
• Subtask 3: 7 / 7
• Subtask 4: 10 / 10
• Subtask 5: 20 / 20
• Subtask 6: 23 / 23
• Subtask 7: 26 / 26