Submission #1126087

#	Time	Username	Problem	Language	Result	Execution time	Memory
1126087		m_bezrutchka	Dreaming (IOI13_dreaming)	C++20	47 / 100	61 ms	17856 KiB

dreaming

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

typedef pair<int, int> pii;

const int MAXN = 1e5 + 10;
vector<pii> adj[MAXN];
int n, distante;
int dist[MAXN];
pii pai[MAXN];
bool mrk_1[MAXN], mrk_2[MAXN];
vector<int> curr;
int diam;

void dfs(int v) {
    mrk_2[v] = true;
    mrk_1[v] = true;
    curr.push_back(v);
    if (dist[distante] < dist[v]) {
        distante = v;
    }
    for (auto [w, nc]: adj[v]) {
        if (pai[v].first == w) continue;
        pai[w] = {v, nc};
        dist[w] = dist[v] + nc;
        dfs(w);
    }
}

int compute_radius() {
    int v = distante;
    vector<int> all_c;
    int tot = 0;
    while (v != -1) {
        tot += pai[v].second;
        all_c.push_back(pai[v].second);
        v = pai[v].first;
    }
    int l = 0, r = tot;
    int resp = tot;
    for (int x: all_c) {
        l += x;
        r -= x;
        resp = min(resp, max(l, r));
    }
    return resp;
}

int find_radius(int v) {
    curr.clear();
    distante = v;
    pai[v] = {-1, 0};
    dist[v] = 0;
    dfs(v);

    for (int x: curr) {
        mrk_1[x] = false;
    }
    pai[distante] = {-1, 0};
    dist[distante] = 0;
    dfs(distante);
    diam = max(diam, dist[distante]);

    return compute_radius();
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    n = N;
    for (int i = 0; i < n; i++) {
        pai[i] = {-1, 0};
    }
    for (int i = 0; i < M; i++) {
        adj[A[i]].push_back({B[i], T[i]});
        adj[B[i]].push_back({A[i], T[i]});
    }
    if (M == N - 1) {
        find_radius(0);
        return diam;
    }
    multiset<int> rs;
    for (int root = 0; root < n; root++) {
        if (mrk_2[root]) continue;
        int r = find_radius(root);
        rs.insert(r);
    }
    auto it = rs.rbegin();
    int large_r = *it;
    it++;
    int large_r_2 = *it;
    return max(diam, large_r + large_r_2 + L);
}

• Subtask 1: 14 / 14
• Subtask 2: 10 / 10
• Subtask 3: 23 / 23
• Subtask 4: 0 / 18
• Subtask 5: 0 / 12
• Subtask 6: 0 / 23