#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx,popcnt,sse4,abm")
#include <bits/stdc++.h>
using namespace std;
int n;int D;
vector<int>e[200005];
int dph[200005];
int tak[200005];
vector<int>dfn;
int rdfn[1000006];
void dfs(int nw,int pa){
dfn.push_back(nw);
rdfn[nw]=dfn.size()-1;
dph[nw]=dph[pa]+1;
for(int i=0;i<e[nw].size();i++){
int v=e[nw][i];
if(v==pa){continue;}
dfs(v,nw);
dfn.push_back(nw);
}
}
int dis[200005];
void bfs(vector<int>st){
queue<int>q;
for(int i=1;i<=n;i++){
dis[i]=1e9;
}
for(int i=0;i<st.size();i++){
q.push(st[i]);
dis[st[i]]=0;
}
while(q.size()){
int nw=q.front();
q.pop();
for(int i=0;i<e[nw].size();i++){
int v=e[nw][i];
if(dis[v]<=n){continue;}
dis[v]=dis[nw]+1;
q.push(v);
}
}
}
int rmq[22][500005];
int lca(int a,int b){
int l=rdfn[a];int r=rdfn[b];
if(r<l){swap(l,r);}
int lg=__lg(r-l+1);
int ret=rmq[lg][l];
if(dph[ret]>dph[rmq[lg][r-(1<<lg)+1]]){
ret=rmq[lg][r-(1<<lg)+1];
}
return ret;
}
int dst(int a,int b){
int lc=lca(a,b);
return dph[a]+dph[b]-dph[lc]*2;
}
signed main()
{
dfn.push_back(0);
cin>>n>>D;
for(int i=2;i<=n;i++){
int v;
cin>>v;
v++;
e[v].push_back(i);
e[i].push_back(v);
}
dfs(1,0);
vector<pair<int,int>>seq;
for(int i=1;i<=n;i++){
seq.push_back({dph[i],i});
}
sort(seq.begin(),seq.end());
reverse(seq.begin(),seq.end());
for(int i=1;i<dfn.size();i++){
rmq[0][i]=dfn[i];
}
for(int i=1;i<=20;i++){
for(int j=1;j<dfn.size();j++){
if( (j+(1<<i)-1)>=dfn.size()){break;}
rmq[i][j]=rmq[i-1][j];
if(dph[rmq[i][j]]>dph[rmq[i-1][j+(1<<(i-1))]]){
rmq[i][j]=rmq[i-1][j+(1<<(i-1))];
}
}
}
int B=450;
vector<int>ans;
ans.push_back(seq[0].second);
tak[seq[0].second]++;
bfs(ans);int lst=0;
for(int i=1;i<seq.size();i++){
int nw=seq[i].second;
if(dis[nw]>=D){
int ok=1;
for(int j=i-1;j>lst;j++){
int v=seq[j].second;
if(tak[v]){
if(dst(nw,v)<D){ok=0;break;}
}
}
if(ok){ans.push_back(nw);tak[nw]=1;}
}
if(i%450==0){
bfs(ans);
lst=i;
}
}
cout<<ans.size();
}
Compilation message
catinatree.cpp: In function 'void dfs(int, int)':
catinatree.cpp:16:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
16 | for(int i=0;i<e[nw].size();i++){
| ~^~~~~~~~~~~~~
catinatree.cpp: In function 'void bfs(std::vector<int>)':
catinatree.cpp:29:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
29 | for(int i=0;i<st.size();i++){
| ~^~~~~~~~~~
catinatree.cpp:36:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
36 | for(int i=0;i<e[nw].size();i++){
| ~^~~~~~~~~~~~~
catinatree.cpp: In function 'int main()':
catinatree.cpp:78:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
78 | for(int i=1;i<dfn.size();i++){
| ~^~~~~~~~~~~
catinatree.cpp:82:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
82 | for(int j=1;j<dfn.size();j++){
| ~^~~~~~~~~~~
catinatree.cpp:83:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
83 | if( (j+(1<<i)-1)>=dfn.size()){break;}
| ~~~~~~~~~~~~^~~~~~~~~~~~
catinatree.cpp:97:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
97 | for(int i=1;i<seq.size();i++){
| ~^~~~~~~~~~~
catinatree.cpp:90:9: warning: unused variable 'B' [-Wunused-variable]
90 | int B=450;
| ^
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
8 ms |
9940 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
8 ms |
9940 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
8 ms |
9940 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
