Submission #1321791

#	Time	Username	Problem	Language	Result	Execution time	Memory
1321791		benjaminkleyn	Migrations (IOI25_migrations)	C++20	0 / 100	40 ms	1192 KiB

migrations

#include "migrations.h"
#include <bits/stdc++.h>
using namespace std;

int n;
int P[10000];
vector<int> g[10000];
int dist[10000] = {0};
void dfs(int u, int p = -1)
{
    if (p == -1) dist[u] = 0;
    for (int v : g[u]) if (v != p) {
        dist[v] = dist[u] + 1;
        dfs(v, u);
    }
}

int prev_a, prev_b;
int a, b;
void find_diameter()
{
    prev_a = a;
    prev_b = b;
    a = b = 0;
    dfs(0);
    for (int i = 0; i < n; i++)
        if (dist[i] > dist[a])
            a = i;

    dfs(a);
    for (int i = 0; i < n; i++)
        if (dist[i] > dist[b])
            b = i;
    int max_dist = dist[b];

    // can we keep one of the two the same?
    dfs(prev_a);
    for (int i = 0; i < n; i++)
        if (dist[i] == max_dist) {
            a = prev_a, b = i;
            return;
        }

    dfs(prev_b);
    for (int i = 0; i < n; i++)
        if (dist[i] == max_dist) {
            b = prev_b, a = i;
            return;
        }
}

int a_send, b_send;
int send_message(int N, int i, int Pi)
{
    n = N;
    g[i].push_back(Pi);
    g[Pi].push_back(i);

    if (i == N - 28) {
        find_diameter();
        a_send = a;
        b_send = b;
        if ((b - a + N) % N < (a - b + N) % N) {
            a_send = a;
            b_send = (b - a + N) % N;
        } else {
            a_send = b;
            b_send = (a - b + N) % N;
            swap(a, b);
            swap(prev_a, prev_b);
        }
    }

    if (N - 27 <= i && i < N - 13) {
        find_diameter();
        int send = (a_send >> (i - (N - 27))) & 0b1;
        if (a == i)
            send = 4;
        if (b == i)
            send |= 2;
        return send;
    }
    if (N - 13 <= i && i < N) {
        find_diameter();
        int send = (b_send >> (i - (N - 13))) & 0b1;
        if (a == i)
            send |= 2;
        if (b == i)
            send = 4;
        return send;
    }
    return 0;
}

pair<int, int> longest_path(vector<int> S)
{
    int N = S.size();
    int a = 0, b = 0;

    for (int i = N - 27; i < N - 13; i++)
        a |= (S[i] & 1) << (i - (N - 27));
    for (int i = N - 13; i < N; i++)
        b |= (S[i] & 1) << (i - (N - 13));
    b = (a + b) % N;

    for (int i = N - 27; i < N - 13; i++) {
        if (S[i] == 4)
            a = i;
        if (S[i] & 2)
            b = i;
    }
    for (int i = N - 13; i < N; i++) {
        if (S[i] == 4)
            b = i;
        if (S[i] & 2)
            a = i;
    }

    return {a, b};
}

• Subtask 0: 0 / 0
• Subtask 1: 0 / 30
• Subtask 2: 0 / 70