Submission #835454

#	Time	Username	Problem	Language	Result	Execution time	Memory
835454		Desh03	Stations (IOI20_stations)	C++17	0 / 100	5 ms	840 KiB

stations

#include "stations.h"

#include <bits/stdc++.h>

using namespace std;

vector<vector<int>> g, up;
vector<int> in, en, dep;
int t, lg;

void dfs(int u) {
    in[u] = t++;
    for (int i = 1; i < lg; i++) {
        up[i][u] = up[i - 1][up[i - 1][u]];
    }
    for (int v : g[u]) {
        if (up[0][u] ^ v) {
            up[0][v] = u;
            dep[v] = dep[u] + 1;
            dfs(v);
        }
    }
    en[u] = t;
}

bool upper(int u, int v) {
    return in[u] <= in[v] && en[v] <= en[u];
}

vector<int> label(int n, int k, vector<int> u, vector<int> v) {
    lg = t = 0, g = vector<vector<int>> (n), in = en = dep = vector<int> (n);
    while ((1 << lg) <= n) ++lg;
    up = vector<vector<int>> (lg, vector<int> (n));
    for (int i = 0; i < n - 1; i++) {
        g[u[i]].push_back(v[i]);
        g[v[i]].push_back(u[i]);
    }
    dfs(0);
    vector<int> ret(n);
    iota(ret.begin(), ret.end(), 0);
    return ret;
}

int kth(int u, int k) {
    for (int i = 0; i < lg; i++) {
        if (k >> i & 1) {
            u = up[i][u];
        }
    }
    return u;
}

int find_next_station(int s, int t, vector<int> c) {
    if (!upper(s, t)) return up[0][s];
    return kth(t, dep[t] - dep[s] - 1);
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 8
• Subtask 3: 0 / 16
• Subtask 4: 0 / 10
• Subtask 5: 0 / 61