Submission #378168

#	Time	Username	Problem	Language	Result	Execution time	Memory
378168		YJU	Cat in a tree (BOI17_catinatree)	C++14	100 / 100	139 ms	24616 KiB

catinatree

#include<bits/stdc++.h>
#pragma GCC optimize("unroll-loops,no-stack-protector,Ofast")
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pll;
const ll N=2e5+5;
const ll MOD=1e9+7;
const ld pi=acos(-1);
#define REP(i,n) for(int i=0;i<n;i++)
#define REP1(i,n) for(int i=1;i<=n;i++)
#define pb push_back
#define mp make_pair
#define X first
#define Y second
#define lwb lower_bound
#define SZ(_a) (ll)_a.size()

vector<ll> v[N];
ll n,x,d;

pll DFS(ll nd,ll pa){
	vector<pll> lis;
    for(auto i:v[nd]){
		if(i==pa)continue;
		lis.pb(DFS(i,nd));
    }
    if(SZ(lis)==0){return mp(1,1);}
    sort(lis.begin(),lis.end(),greater<pll>());
    ll pos=0;
    for(int i=1;i<SZ(lis);i++){
		if(lis[i-1].X+lis[i].X>=d)pos=i;
    }
    ll ret=0;
    REP(i,SZ(lis))ret+=lis[i].Y-1;
    ret+=pos+1;
    if(lis[pos].X>=d)return mp(1,ret+1);
    else return mp(lis[pos].X+1,ret);
}

int main(){
	ios_base::sync_with_stdio(0);cin.tie(0);
    cin>>n>>d;
    for(int i=1;i<n;i++)cin>>x,v[x].pb(i),v[i].pb(x);
    cout<<DFS(0,-1).Y<<"\n";
	return 0;
}

• Subtask 1: 11 / 11
• Subtask 2: 40 / 40
• Subtask 3: 49 / 49