Submission #164046

#	Time	Username	Problem	Language	Result	Execution time	Memory
164046		nvmdava	Cat in a tree (BOI17_catinatree)	C++17	100 / 100	254 ms	18768 KiB

catinatree

#include <bits/stdc++.h>
#pragma GCC optimize("unroll-loops")
using namespace std;
#define ll long long
#define ff first
#define ss second
#define pb push_back
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
#define N 200005
#define INF 0x3f3f3f3f
#define MOD 1000000007LL

int d[N];
vector<int> adj[N];
vector<int> v;

void dfs(int v, int p){
	d[v] = d[p] + 1;
	for(int& x : adj[v]){
		if(x == p) continue;
		dfs(x, v);
	}
}

void dfs2(int v, int t){
	d[v] = -t;
	if(t == 1) return;
	t--;
	for(int& x : adj[v]){
		if(d[x] > -t){
			dfs2(x, t);
		}
	}
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int n, t;
    cin>>n>>t;
    for(int i = 1; i < n; i++){
    	int v, u;
    	cin>>u;
    	++u;
    	v = i + 1;
    	adj[v].push_back(u);
    	adj[u].push_back(v);
    	::v.push_back(i);
    }
    ::v.push_back(n);

    dfs(1, 0);
    sort(v.begin(), v.end(),[](const int& lhs, const int& rhs){
    	return d[lhs] > d[rhs];
    });
    int ans = 0;
	for(int& a : v){
		if(d[a] > 0){
			ans++;
			dfs2(a, t);
		}
	}
	cout<<ans;
}

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