Submission #929149

#	Time	Username	Problem	Language	Result	Execution time	Memory
929149		imarn	Cat Exercise (JOI23_ho_t4)	C++14	100 / 100	236 ms	44628 KiB

Main

#include<bits/stdc++.h>
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
#define f first
#define s second
#define pb push_back
#define all(x) x.begin(),x.end()
#define vi vector<int>
#define vvi vector<vi>
#define vp vector<pii>
using namespace std;
const int N=2e5+5;
vector<int>g[N];
int pr[N],up[N][21],dep[N],h[N];
ll dp[N]{0};
int get(int r){
    return pr[r]==r?r:pr[r]=get(pr[r]);
}
void dfs(int u,int p,int l){
    up[u][0]=p;dep[u]=l;
    for(int i=1;i<=20;i++)up[u][i]=up[up[u][i-1]][i-1];
    for(auto v:g[u]){
        if(v==p)continue;
        dfs(v,u,l+1);
    }
}
int qr(int a,int b){
    if(dep[a]>dep[b])swap(a,b);
    for(int i=20;i>=0;i--)if(dep[up[b][i]]>=dep[a])b=up[b][i];
    if(a==b)return a;
    for(int i=20;i>=0;i--)if(up[a][i]!=up[b][i])a=up[a][i],b=up[b][i];
    return up[a][0];
}
int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);
    int n;cin>>n;
    for(int i=1;i<=n;i++)cin>>h[i];
    for(int i=1,u,v;i<=n-1;i++){
        cin>>u>>v;g[h[u]].pb(h[v]);g[h[v]].pb(h[u]);
    }iota(pr,pr+n+1,0);dfs(1,1,0);
    for(int i=2;i<=n;i++){
        for(auto v:g[i]){
            int p=get(v);
            if(p<i)dp[i]=max(dp[i],dp[p]+dep[p]+dep[i]-2*dep[qr(i,p)]),pr[p]=i;
        }
    }cout<<dp[n];
}

• 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