Submission #553745

#	Time	Username	Problem	Language	Result	Execution time	Memory
553745		new_acc	Cat in a tree (BOI17_catinatree)	C++14	100 / 100	103 ms	29724 KiB

catinatree

#include<bits/stdc++.h>
#define fi first
#define se second
#define pitem item*
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<ll> vl;
const int N=2e5+10;
const int SS=1<<19;
const int INFi=2e9;
const ll INFl=1e13;
const ll mod2=998244353;
const ll mod=1e9+7;
const ll mod3=1000696969;
const ll p=70032301;
const ull p2=913;
const int L=20;
vi graf[N];
pair<int,int> dp[N];
int n,k;
void dfs(int v,int o){
	vector<pair<int,int> >curr;
	int aktsum=0;
	for(auto u:graf[v]){
		if(u==o) continue;
		dfs(u,v);
		curr.push_back({dp[u].se,dp[u].fi});
		aktsum+=dp[u].fi;
	}
	sort(curr.begin(),curr.end());
	auto bs=[&](int pocz,int kon,int x){
		int sr,res=pocz;
		pocz++;
		while(pocz<=kon){
			sr=(pocz+kon)>>1;
			if(curr[sr].fi+x+2<k) res=sr,pocz=sr+1;
			else kon=sr-1;
		}
		return res;	
	};
	dp[v].fi=0;
	for(int i=0;i<curr.size();i++){
		pair<int,int> akt;
		akt.fi=aktsum-i-(bs(i,curr.size()-1,curr[i].fi)-i);
		akt.se=curr[i].fi+1;
		if(akt.fi>dp[v].fi or (akt.fi==dp[v].fi and akt.se>dp[v].se)) dp[v]=akt;
	}
	for(auto u:graf[v]){
		if(u==o) continue;
		if(dp[u].se!=k-1) aktsum--;
	}
	aktsum++;
	if(aktsum>dp[v].fi) dp[v]={aktsum,0};
}
void solve(){
	cin>>n>>k;
	for(int a,i=2;i<=n;i++){
		cin>>a;
		a++;
		graf[i].push_back(a),graf[a].push_back(i);
	}
	dfs(1,1);
	cout<<dp[1].fi<<"\n";
}
int main(){
	ios_base::sync_with_stdio(0),cin.tie(0);
	solve();
}

Compilation message (stderr)

catinatree.cpp: In function 'void dfs(int, int)':
catinatree.cpp:44:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |  for(int i=0;i<curr.size();i++){
      |              ~^~~~~~~~~~~~

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