Submission #961027

#	Time	Username	Problem	Language	Result	Execution time	Memory
961027		tudor_costin	Cat Exercise (JOI23_ho_t4)	C++11	100 / 100	329 ms	194720 KiB

Main

#include <bits/stdc++.h>
#define int long long
using namespace std;
const int Nmax=3e5;
int a[Nmax];
int nodes[Nmax],pos[Nmax],p[Nmax];
pair<int,int> maxi[Nmax];
int dp[Nmax];
int nodedepth[Nmax];
pair<int,int> rmq[35][2*Nmax];
vector<int> euler;
vector<int> depths;
vector<int> v[Nmax];
int n;
int sol=0;
int sef(int x)
{
    if(p[x]==x) return x;
    p[x]=sef(p[x]);
    return p[x];
}
bool cmp(int x,int y)
{
    return a[x]<a[y];
}
void dfs(int nod,int prev,int depth)
{
    euler.push_back(nod);
    depths.push_back(depth);
    nodedepth[nod]=depth;
    pos[nod]=euler.size()-1;
    for(auto u:v[nod])
    {
        if(u!=prev)
        {
            dfs(u,nod,depth+1);
            euler.push_back(nod);
            depths.push_back(depth);
        }
    }
}int lg(int x)
{
    return 31-__builtin_clz(x);
}
int query(int l,int r)
{
    int len=lg(r-l+1);
    return min(rmq[len][l],rmq[len][r-(1<<len)+1]).second;
}
int lca(int u,int v)
{
    if(pos[u]>pos[v]) swap(u,v);
    return query(pos[u],pos[v]);
}
void calclca()
{
    dfs(1,0,0);
    int k=lg(euler.size());
    for(int j=0;j<euler.size();j++)
    {
        rmq[0][j]={depths[j],euler[j]};
    }
    for(int i=1;i<=k;i++)
    {
        for(int j=0;j+(1<<i)<euler.size();j++)
        {
            rmq[i][j]=min(rmq[i-1][j],rmq[i-1][j+(1<<(i-1))]);
        }
    }
}
int dist(int u,int v)
{
    int nod=lca(u,v);
    return nodedepth[u]+nodedepth[v]-2*nodedepth[nod];
}
void unite(int x,int y)
{
    int sefx=sef(x);
    int sefy=sef(y);
    p[sefy]=sefx;
    maxi[sefx]=max(maxi[sefx],maxi[sefy]);
    return;
}
void activate(int nod)
{
    p[nod]=nod;
    maxi[nod]={a[nod],nod};
    for(auto u:v[nod])
    {
        if(p[u]!=0)
        {
            int nxt=maxi[sef(u)].second;
            dp[nod]=max(dp[nod],dist(nod,nxt)+dp[nxt]);
            unite(nod,u);
        }
    }
}
signed main()
{
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>a[i];
        nodes[i]=i;
    }
    sort(nodes+1,nodes+n+1,cmp);
    for(int i=1;i<n;i++)
    {
        int x,y;
        cin>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    calclca();
    for(int i=1;i<=n;i++)
    {
        activate(nodes[i]);
    }
    cout<<dp[nodes[n]]<<'\n';
    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'void calclca()':
Main.cpp:59:18: 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]
   59 |     for(int j=0;j<euler.size();j++)
      |                 ~^~~~~~~~~~~~~
Main.cpp:65:29: 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]
   65 |         for(int j=0;j+(1<<i)<euler.size();j++)
      |                     ~~~~~~~~^~~~~~~~~~~~~

• 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