Submission #870595

#	Time	Username	Problem	Language	Result	Execution time	Memory
870595		sleepntsheep	Cat in a tree (BOI17_catinatree)	C++17	100 / 100	61 ms	24484 KiB

catinatree

#include <iostream>
#include <cstring>
#include <vector>
#include <algorithm>
#include <deque>
#include <set>
#include <utility>
#include <array>
#include <cassert>

#pragma GCC optimize("O2,unroll-loops")
#pragma GCC target("avx2,tune=native")



using namespace std;
#define ALL(x) x.begin(), x.end()
#define ShinLena cin.tie(nullptr)->sync_with_stdio(false);
using i64 = long long;
#define N 200005

int n, d, t[N];
vector<int> g[N];
array<int, 2> dp[N];

void upd(int p, int k) {;for (; p ; p-=p&-p) t[p] += k; }
int qry(int p) { ; int z = 0; for (; p < N; p+=p&-p) z += t[p]; return z; }

void dfs(int u, int dep)
{
    int base = 0, fs = 1e9;

    for (auto v : g[u]) 
    {
        dfs(v, dep+1), base += dp[v][0] - 1;
        if (dp[v][1] >= dep + (d+1)/2)
            fs = min(fs, dp[v][1]);
    }

    for (auto v : g[u]) upd(dp[v][1], 1);

    dp[u] = {base + 1 + qry(d + dep), dep};

    for (auto v : g[u])
    {
        if (dp[v][1] < dep + (d+1)/2)
        {
            upd(dp[v][1], -1);
            dp[u] = max(dp[u], {base + 1 + qry(dep + max((d+1)/2, d - (dp[v][1] - dep))), dp[v][1]});
            upd(dp[v][1], 1);
        }
        else
        {
            dp[u] = max(dp[u], {base + qry(dep + (d+1)/2), fs});
        }
    }

    for (auto v : g[u]) upd(dp[v][1], -1);
}

int main()
{
    ShinLena;
    cin >> n >> d;
    for (int i = 1, v; i < n; ++i) cin >> v, g[v].push_back(i);
    dfs(0, 1);
    cout << dp[0][0];

    return 0;
}

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