Submission #1265505

#	Time	Username	Problem	Language	Result	Execution time	Memory
1265505		syanvu	Cat Exercise (JOI23_ho_t4)	C++20	100 / 100	256 ms	64628 KiB

Main

#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp> 
// #include <ext/pb_ds/tree_policy.hpp>

#define SS ios_base::sync_with_stdio(0);cin.tie(nullptr);cout.tie(nullptr);
#pragma optimize("g", on)
#pragma GCC optimize("03")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,avx2,mmx,fma,avx,tune=native")
#define int long long
#define all(x) x.begin(),x.end()
#define F first
#define S second


using namespace std;
// using namespace __gnu_pbds; 
// #define ordered_set tree<int,null_type,less_equal<int>,rb_tree_tag,tree_order_statistics_node_update>

const int LG = 20,N = 2e5+1,inf = 1e18,MOD = 998244353;
const double eps = 1e-9;
int T;

vector<int> g[N];
int h[N];
int dep[N],up[N][21],tin[N],tout[N],timer,dp[N];

int par[N],sz[N];

void calc(int v,int p){
    tin[v]=++timer;
    up[v][0]=p;
    for(int i=1;i<=20;i++){
        up[v][i]=up[up[v][i-1]][i-1];
    }
    for(int to:g[v]){
        if(to==p) continue;
        dep[to]=dep[v]+1;
        calc(to,v);
    }
    tout[v]=timer;
}
bool ch(int u,int v){
    return (tin[u]<=tin[v] && tout[u]>=tout[v]);
}
int lca(int u,int v){
    if(ch(u,v)) return u;
    if(ch(v,u)) return v;
    for(int i=20;i>=0;i--){
        if(!ch(up[u][i],v)) u=up[u][i];
    }
    return up[u][0];
}
int find(int v){
    if(par[v]==v) return v;
    return par[v]=find(par[v]);
}
void dsu(int u,int v){
    u=find(u);
    v=find(v);
    if(u==v) return;
    if(h[u]<h[v]) swap(u,v);
    par[v]=u;
}

void solve() {
    int n;
    cin>>n;
    int ord[n+1]={};
    for(int i=1;i<=n;i++){
        cin>>h[i];
        ord[h[i]]=i;
        par[i]=i;
    }
    for(int i=1;i<n;i++){
        int u,v;
        cin>>u>>v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    calc(1,1);
    for(int i=1;i<=n;i++){
        int v=ord[i];
        for(int to:g[v]){
            if(h[to]>h[v]) continue;
            int root=find(to);
            dp[v]=max(dp[v],dp[root]+dep[root]+dep[v]-2*dep[lca(root,v)]);
            dsu(to,v);
        }
    }
    cout<<dp[ord[n]];
    return;
}
signed main() {
    //   freopen("deleg.in","r",stdin);    
    // freopen("deleg.out","w",stdout);
    SS
    int t = 1;
    if (T) {
        cin >> t;
    }
    while (t--) {
        solve();
    }
}
/*
*/

• 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