Submission #1095380

#	Time	Username	Problem	Language	Result	Execution time	Memory
1095380		abcvuitunggio	Cat Exercise (JOI23_ho_t4)	C++17	100 / 100	307 ms	77652 KiB

Main

#include <bits/stdc++.h>
#define int long long
using namespace std;
int n,h[200001],p[200001][20],d[200001],pos[200001],l[200001],u,v,mx[200001],res;
vector <int> ke[200001],ke2[200001];
void dfs(int u, int par){
    for (int v:ke[u])
        if (v!=par){
            p[v][0]=u;
            for (int i=1;i<20;i++)
                p[v][i]=p[p[v][i-1]][i-1];
            d[v]=d[u]+1;
            dfs(v,u);
        }
}
int lca(int u, int v){
    if (d[u]<d[v])
        swap(u,v);
    for (int i=19;i>=0;i--)
        if (d[p[u][i]]>=d[v])
            u=p[u][i];
    if (u==v)
        return u;
    for (int i=19;i>=0;i--)
        if (p[u][i]!=p[v][i]){
            u=p[u][i];
            v=p[v][i];
        }
    return p[u][0];
}
int dist(int u, int v){
    return d[u]+d[v]-d[lca(u,v)]*2;
}
int f(int i){
    return (l[i]==i?i:l[i]=f(l[i]));
}
void unite(int i, int j){
    i=f(i),j=f(j);
    l[i]=j;
    mx[j]=max(mx[i],mx[j]);
}
void dfs2(int u, int val){
    res=max(res,val);
    for (int v:ke2[u])
        dfs2(v,val+dist(u,v));
}
int32_t main(){
    ios_base::sync_with_stdio(NULL);cin.tie(nullptr);
    cin >> n;
    for (int i=1;i<=n;i++){
        cin >> h[i];
        pos[h[i]]=i;
        l[i]=i;
        mx[i]=h[i];
    }
    for (int i=1;i<n;i++){
        cin >> u >> v;
        ke[u].push_back(v);
        ke[v].push_back(u);
    }
    dfs(pos[n],0);
    for (int i=1;i<=n;i++){
        int u=pos[i];
        for (int j:ke[u])
            if (h[j]<h[u]){
                int v=pos[mx[f(j)]];
                ke2[u].push_back(v);
                unite(u,j);
            }
    }
    dfs2(pos[n],0);
    cout << res;
}

• 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