Submission #1074016

#	Time	Username	Problem	Language	Result	Execution time	Memory
1074016		Ignut	Dreaming (IOI13_dreaming)	C++17	100 / 100	125 ms	18900 KiB

dreaming

// Ignut

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

using namespace std;
using ll = long long;

const int INF = 1e9 + 123;
const int MAXN = 1e5 + 123;

vector<pair<int, int>> tree[MAXN];
int dist[MAXN];

void dfs(int v, int par, int d) {
    dist[v] = d;
    for (auto [to, w] : tree[v])
        if (to != par)
            dfs(to, v, d + w); 
}

void FindDist(int source) {
    dfs(source, -1, 0);
}

bool used[MAXN];
vector<int> comp;

void dfs0(int v, int par = -1) {
    used[v] = true;
    comp.push_back(v);
    for (auto [to, w] : tree[v])
        if (to != par)
            dfs0(to, v);
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    for (int i = 0; i < N; i ++) {
        tree[i].clear();
        used[i] = false;
    }
    for (int i = 0; i < M; i ++) {
        tree[A[i]].push_back({B[i], T[i]});
        tree[B[i]].push_back({A[i], T[i]});
    }
    
    vector<pair<int, int>> c;
    for (int i = 0; i < N; i ++) {
        if (used[i]) continue;
        comp.clear();
        dfs0(i);
        FindDist(i);

        int j = i;
        for (int v : comp) if (dist[v] > dist[j]) j = v;
        FindDist(j);

        map<int, int> d1;
        for (int v : comp) d1[v] = dist[v];

        j = i;
        for (int v : comp) if (dist[v] > dist[j]) j = v;
        FindDist(j);

        int ctr = i, maxDist = INF;
        for (int v : comp) {
            int d = max(d1[v], dist[v]);
            if (d < maxDist) {
                ctr = v;
                maxDist = d;
            }
        }
        c.push_back({maxDist, ctr});
    }
    sort(c.begin(), c.end());
    reverse(c.begin(), c.end());
    for (int i = 1; i < c.size(); i ++) {
        tree[c[i].second].push_back({c[0].second, L});
        tree[c[0].second].push_back({c[i].second, L});
    }

    int res = 0;
    FindDist(0);
    int j = 0;
    for (int i = 0; i < N; i ++) if (dist[i] > dist[j]) j = i;
    FindDist(j);
    for (int i = 0; i < N; i ++) res = max(res, dist[i]);
    return res;
}

Compilation message (stderr)

dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:77:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   77 |     for (int i = 1; i < c.size(); i ++) {
      |                     ~~^~~~~~~~~~

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