Submission #493544

#	Time	Username	Problem	Language	Result	Execution time	Memory
493544		nohaxjustsoflo	Cat in a tree (BOI17_catinatree)	C++17	100 / 100	213 ms	34768 KiB

catinatree

#include <bits/stdc++.h>
#include <iostream>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
typedef tree<ll,null_type,less_equal<ll>,rb_tree_tag,tree_order_statistics_node_update> order_set;
//mt19937 mt_rand(chrono::high_resolution_clock::now().time_since_epoch().count());
//uniform_int_distribution<int> gen; ///(min, max)
//int random() {return gen(mt_rand);}
const int mxN = 5e5+5;
const int mod = 998244353;
const int mxlogN = 20;
const int mxK = 26;
const ll inf = 1e9;

vector<int> adj[mxN];
int down[mxN];
int p[mxN];
int in[mxN], out[mxN], _timer;
void dfs(int i)
{
    in[i] = _timer++;
    for(int j : adj[i])
    {
        if(j==p[i]) continue;
        p[j] = i;
        down[j] = down[i]+1;
        dfs(j);
    }
    out[i] = _timer;
}
struct segTree
{
    struct node
    {
        ll mn;
    };
    int size;
    vector<node> val; /// minimum, sum count
    void build(int n)
    {
        size = 1;
        while(size < n) size <<= 1;
        val = vector<node>(size << 1, {inf});
    }
    void set(int l, int r, ll v, int i, int Lx, int Rx)
    {
        if(Rx <= l || Lx >= r) return;
        if(Lx >= l && Rx <= r)
        {
            val[i].mn = min(val[i].mn, v);
            return;
        }
        int m = (Rx+Lx)/2;
        set(l, r, v, i*2+1, Lx, m);
        set(l, r, v, i*2+2, m, Rx);
    }
    void set(int l, int r, ll v)
    {
        set(l, r, v, 0, 0, size);
    }
    ll query(int pos, int i, int Lx, int Rx)
    {
        if(Rx-Lx==1) return val[i].mn;
        int m = (Rx+Lx)/2;
        if(pos<m) return min(val[i].mn, query(pos, i*2+1, Lx, m));
        return min(val[i].mn, query(pos, i*2+2, m, Rx));
    }
    ll query(int i)
    {
        return query(i, 0, 0, size);
    }
};

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int n, d; cin >> n >> d;
    for(int i = 2; i <= n; i++)
    {
        int x; cin >> x; x++;
        adj[x].push_back(i);
        adj[i].push_back(x);
    }
    dfs(1);
    vector<pair<int,int>> v;
    for(int i = 1; i <= n; i++) v.push_back({down[i], i});
    sort(v.begin(), v.end());
    reverse(v.begin(), v.end());
    segTree tree;
    tree.build(n);
    vector<int> ans;
    for(auto par : v)
    {
        int x = par.second;
        if(tree.query(in[x])+down[x] < d) continue;
        ans.push_back(x);
        int h = 0;
        int H = down[x];
        while(x&&h<=d)
        {
            tree.set(in[x], out[x], H-2*down[x]);
            x = p[x];
            h++;
        }
    }
    cout << ans.size() << "\n";
}

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