Submission #870253

#	Time	Username	Problem	Language	Result	Execution time	Memory
870253		sleepntsheep	Cat in a tree (BOI17_catinatree)	C++17	0 / 100	1 ms	2396 KiB

catinatree

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

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, l[N], h[N], alloc = 1, dp[N][2], t[N];
pair<int, int> g[N<<1];

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 add_edge(int u, int v)
{
    int p = alloc++;
    g[p] = {v, h[u]};
    h[u] = p;
}

void dfs(int u, int p = -1, int dep = 1)
{
    l[u] = dep;
    int base = 0;
    for (auto j = h[u]; j; j = g[u].second)
    {
        int v = g[u].first;
        if (v == p) continue;
        dfs(v, u, dep+1);
        base += dp[v][0] - 1;
        upd(dp[v][1], 1);
    }
    dp[u][0] = base + 1, dp[u][1] = l[u];

    for (auto j = h[u]; j; j = g[u].second)
    {
        int v = g[u].first;
        if (v == p) continue;
        int sel = base + 1 + qry(d - (dp[v][1] - dep) + dep);
        if (dp[u][0] < sel)
        {
            dp[u][0] = sel;
            dp[u][1] = dp[v][1];
        }
        else if (dp[u][0] == sel && dp[v][1] > dp[u][1])
        {
            dp[u][1] = dp[v][1];
        }
    }

    for (auto j = h[u]; j; j = g[u].second)
    {
        int v = g[u].first;
        if (v == p) continue;
        upd(dp[v][1], -1);
    }
}

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

    return 0;
}

• Subtask 1: 0 / 11
• Subtask 2: 0 / 40
• Subtask 3: 0 / 49