Submission #1032329

#	Time	Username	Problem	Language	Result	Execution time	Memory
1032329		vjudge1	Cat Exercise (JOI23_ho_t4)	C++17	100 / 100	178 ms	66644 KiB

Main

#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define fi first
#define se second
#define for1(i,j,k) for(int i=(j);i<=(k);i++)
#define for2(i,j,k) for(int i=(j);i>=(k);i--)
#define for3(i,j,k,l) for(int i=j;i<=k;i+=l)
#define bit(n,i) ((n>>i)&1)
#define all(x) x.begin(),x.end()
//#pragma GCC optimize("O2,unroll-loops")
//#pragma GCC target("avx,avx2,bmi,bmi2,sse,sse2,sse3,ssse3,sse4,popcnt")
#define int long long
typedef long long ll;
typedef pair<int,int> pii;
typedef long double ld;
typedef pair<ld,ld> pdd;
typedef pair<ll,ll> pll;
const ll maxn=2e5+69;
const ll offset=1e9;
const ll block_sz=317;
const ll inf=1e18;
const ll mod=123456789;
int n,p[maxn],par[maxn];
vector<int> adj[maxn];
int Find(int u)
{
    return par[u]<0?u:par[u]=Find(par[u]);
}
int dep[maxn],up[maxn][21],in[maxn],out[maxn],Time,dp[maxn];
void dfs(int u,int pre)
{
    in[u]=++Time;
    up[u][0]=pre;
    for1(i,1,20) up[u][i]=up[up[u][i-1]][i-1];
    for(int v:adj[u])
    {
        if (v==pre) continue;
        dep[v]=dep[u]+1;
        dfs(v,u);
    }
    out[u]=Time;
}
bool is_ancestor(int u,int v)
{
    return in[u]<=in[v] && out[v]<=out[u];
}
int lca(int u,int v)
{
    if (is_ancestor(u,v)) return u;
    if (is_ancestor(v,u)) return v;
    for2(i,20,0) if (!is_ancestor(up[u][i],v)) u=up[u][i];
    return up[u][0];
}
void sol()
{
    cin >> n;
    for1(i,1,n) cin >> p[i];
    for1(i,1,n-1)
    {
        int u,v; cin>> u>> v;
        u=p[u],v=p[v];
        adj[u].pb(v);
        adj[v].pb(u);
    }
    dfs(1,1);
    for1(i,1,n) par[i]=-1;
    for1(u,1,n)
    {
        for(int v:adj[u])
        {
            v=Find(v);
            if (v<u)
            {
                par[v]=u;
                dp[u]=max(dp[u],dp[v]+dep[u]+dep[v]-2*dep[lca(u,v)]);
            }
        }
    }
    cout << dp[n];

}

int32_t main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
//    freopen("PAINT.inp","r",stdin);
//    freopen("PAINT.out","w",stdout);
    int t=1;//cin >> t;
    while (t--)
    {
        sol();
    }
}
/*
*/

• 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