Submission #832914

#	Time	Username	Problem	Language	Result	Execution time	Memory
832914		winter0101	Cat Exercise (JOI23_ho_t4)	C++14	41 / 100	169 ms	77896 KiB

Main

#include <bits/stdc++.h>
using namespace std;
#define all(fl) fl.begin(),fl.end()
#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 lb lower_bound
#define ub upper_bound
#define sz(a) (int)a.size()
#define pii pair<int,int>
#define pli pair<long long,int>
#define gcd __gcd
#define lcm(x,y) x*y/__gcd(x,y)
const int maxn=2e5+9;
vector<int>a[maxn];
int b[maxn];
int rev[maxn];
long long ans=0;
int dep[maxn];
int st[maxn][19],jump[maxn][19];
vector<pii>d[maxn];
void dfs(int u,int par){
    for (auto v:a[u]){
        if (v==par)continue;
        dep[v]=dep[u]+1;
        st[v][0]=b[u];
        jump[v][0]=u;
        for1(i,1,18){
        jump[v][i]=jump[jump[v][i-1]][i-1];
        st[v][i]=max(st[v][i-1],st[jump[v][i-1]][i-1]);
        }
        if (dep[v]>0){
            int mx=0;
            int nv=v;
            for2(j,18,0){
            if (st[nv][j]==0)continue;
            if (st[nv][j]<b[v]){
                mx=max(mx,st[nv][j]);
                nv=jump[nv][j];
            }
            }
            if (mx>0)d[v].pb({rev[mx],dep[v]-dep[rev[mx]]});
            nv=st[nv][0];
            d[rev[nv]].pb({v,dep[v]-dep[rev[nv]]});
        }
        dfs(v,u);
    }
}
long long f[maxn];
int32_t main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n;
    cin>>n;
    for1(i,1,n){
    cin>>b[i];
    rev[b[i]]=i;
    }
    for1(i,1,n-1){
    int u,v;
    cin>>u>>v;
    a[u].pb(v);
    a[v].pb(u);
    }
    int root;
    for1(i,1,n)if (b[i]==n)root=i;
    dfs(root,0);
    /*for1(i,1,n){
    for (auto v:d[i]){
        cout<<i<<" "<<v.fi<<" "<< v.se<<'\n';
    }
    }*/
    for1(i,1,n){
    for (auto v:d[rev[i]]){
        f[rev[i]]=max(f[rev[i]],f[v.fi]+v.se);
    }
    ans=max(ans,f[rev[i]]);
    }
    cout<<ans;

}

Compilation message (stderr)

Main.cpp: In function 'int32_t main()':
Main.cpp:70:8: warning: 'root' may be used uninitialized in this function [-Wmaybe-uninitialized]
   70 |     dfs(root,0);
      |     ~~~^~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 7 / 7
• Subtask 3: 7 / 7
• Subtask 4: 0 / 10
• Subtask 5: 20 / 20
• Subtask 6: 0 / 23
• Subtask 7: 0 / 26