#include<bits/stdc++.h>
#define ll long long
#define sz(x) (signed)x.size()
#define pb push_back
#define ff first
#define ss second
#define endl '\n'
#define For(i,l,r) for(int i=l;i<=r;i++)
#define ForD(i,l,r) for(int i=r;i>=l;i--)
using namespace std;
const int N=2e5+3;
int n,p[N],d[N],par[20][N];
int mxChild[N];
ll f[N],dp[N];
vector<int> g[N];
int find_set(int a) {
return (f[a]<0?a:f[a]=find_set(f[a]));
}
void unite(int u,int v) {
int a=find_set(u),b=find_set(v);
if (a==b) return;
if (f[a]>f[b]) swap(a,b);
f[a]+=f[b];
f[b]=a;
}
void predfs(int u,int p=0) {
for(auto v: g[u])
if (v!=p) {
d[v]=d[u]+1;
par[0][v]=u;
For(i,1,18) par[i][v]=par[i-1][par[i-1][v]];
predfs(v,u);
}
}
int lca(int u,int v) {
if (d[v]>d[u]) swap(u,v);
int dd=d[u]-d[v];
For(i,0,18)
if (dd>>i&1) u=par[i][u];
if (u==v) return u;
ForD(i,1,18)
if (par[i][u]!=par[i][v]) u= par[i][u],v=par[i][v];
return par[0][u];
}
int dis(int u,int v) {
return d[u]+d[v]-2*d[lca(u,v)];
}
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n;
For(i,1,n) cin >> p[i];
For(i,1,n-1) {
int u,v;
cin >> u >> v;
g[p[u]].pb(p[v]);
g[p[v]].pb(p[u]);
}
f[1]=-1;
dp[1]=0;
mxChild[1]=1;
predfs(1);
For(i,2,n) {
dp[i]=0;
for(auto u: g[i]) {
if (u>i) continue;
dp[i]=max(dp[i],dp[mxChild[find_set(u)]]+dis(mxChild[find_set(u)],i));
}
f[i]=-1;
for(auto u: g[i])
if (u<=i) unite(i,u);
mxChild[find_set(i)]=i;
}
cout << dp[n] << endl;
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
5208 KB |
Output is correct |
2 |
Correct |
2 ms |
5212 KB |
Output is correct |
3 |
Correct |
2 ms |
5212 KB |
Output is correct |
4 |
Incorrect |
2 ms |
5212 KB |
Output isn't correct |
5 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
5208 KB |
Output is correct |
2 |
Correct |
2 ms |
5212 KB |
Output is correct |
3 |
Correct |
2 ms |
5212 KB |
Output is correct |
4 |
Incorrect |
2 ms |
5212 KB |
Output isn't correct |
5 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
5208 KB |
Output is correct |
2 |
Correct |
2 ms |
5212 KB |
Output is correct |
3 |
Correct |
2 ms |
5212 KB |
Output is correct |
4 |
Incorrect |
2 ms |
5212 KB |
Output isn't correct |
5 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
5208 KB |
Output is correct |
2 |
Correct |
2 ms |
5212 KB |
Output is correct |
3 |
Correct |
2 ms |
5212 KB |
Output is correct |
4 |
Incorrect |
2 ms |
5212 KB |
Output isn't correct |
5 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
5208 KB |
Output is correct |
2 |
Correct |
2 ms |
5212 KB |
Output is correct |
3 |
Correct |
2 ms |
5212 KB |
Output is correct |
4 |
Incorrect |
2 ms |
5212 KB |
Output isn't correct |
5 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
5208 KB |
Output is correct |
2 |
Incorrect |
2 ms |
5212 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
5208 KB |
Output is correct |
2 |
Correct |
2 ms |
5212 KB |
Output is correct |
3 |
Correct |
2 ms |
5212 KB |
Output is correct |
4 |
Incorrect |
2 ms |
5212 KB |
Output isn't correct |
5 |
Halted |
0 ms |
0 KB |
- |