Submission #1257717

#	Time	Username	Problem	Language	Result	Execution time	Memory
1257717		biank	Migrations (IOI25_migrations)	C++20	0 / 100	30 ms	1040 KiB

migrations

#include "migrations.h"
#include <bits/stdc++.h>

using namespace std;

#define forsn(i, s, n) for (int i = int(s); i < int(n); i++)
#define forn(i, n) forsn(i, 0, n)
#define dforsn(i, s, n) for (int i = int(n) - 1; i >= int(s); i--)
#define dforn(i, n) dforsn(i, 0, n)

using vi = vector<int>;
using ll = long long;
using ii = pair<int, int>;

#define fst first
#define snd second

#define sz(x) int(x.size())
#define all(x) begin(x), end(x)

#define pb push_back
#define eb emplace_back

const int N = 100020;
const int K = 14;
const int B = 7;

int up[K][N], depth[N];

int lca(int u, int v) {
    if (depth[u] < depth[v]) swap(u, v);
    int diff = depth[u] - depth[v];
    forn(i, K) if (diff >> i & 1) u = up[i][u];
    if (u == v) return u;
    dforn(i, K) if (up[i][u] != up[i][v]) {
        u = up[i][u], v = up[i][v];
    }
    assert(up[0][u] == up[0][v]);
    return u;
}

int dist(int u, int v) {
    return depth[u] + depth[v] - 2 * depth[lca(u, v)];
}

int u = 0, v = 0;
int oldU, oldV;
int message;
int type = 0;
const int base[3] = {1, 4, 2};

int send_message(int /*N*/, int i, int Pi) {
    up[0][i] = Pi, depth[i] = depth[Pi] + 1;
    forn(j, K - 1) up[j + 1][i] = up[j][up[j][i]];
    int state = 0;
    int distToU = dist(i, u);
    int distToV = dist(i, v);
    int currDiameter = dist(u, v);
    if (distToU > distToV) {
        if (distToU > currDiameter) v = i, state = 2;
    } else {
        if (distToV > currDiameter) u = i, state = 1;
    }
    if (i >= N - K - B) {
        int a = 0;
        forn(b, N) if (dist(0, b) > dist(0, a)) a = b;
        forn(b, N) assert(dist(a, b) <= dist(u, v));
    }
    if (i == N - K - B) message = u, type = 1;
    if (i == N - K) message = v, type = 2;
    if (type == 0) return 0;
    int digit = message % base[type];
    message /= base[type];
    if (type == state) return 4;
    if (type == 2 && state == 1) return digit + 2;
    return digit;
}

ii longest_path(vi S) {
    int U = 0, V = 0;
    dforsn(i, N - K - B, N - K) {
        if (S[i] == 4) {
            U = i;
            break;
        }
        U = U * 4 + S[i];
    }
    dforsn(i, N - K, N) {
        if (S[i] == 4) {
            V = i;
            break;
        }
        V = V * 2 + (S[i] % 2);
    }
    dforsn(i, N - K, N) {
        if (S[i] == 2 || S[i] == 3) {
            U = i;
            break;
        }
    } 
    return {U, V};
}

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