Submission #482428

#	Time	Username	Problem	Language	Result	Execution time	Memory
482428		Spade1	Dreaming (IOI13_dreaming)	C++17	100 / 100	100 ms	13284 KiB

dreaming

#include <bits/stdc++.h>
#include "dreaming.h"
#define ll long long
#define pii pair<int, int>
#define st first
#define nd second
using namespace std;

vector<pii> adj[100010];
vector<int> connect;
bool visited[100010];

int max_dis, min_dis;
int u, v, node;

void dfs(int i, int prt, int dis) {
    visited[i] = 1;
    if (dis > max_dis) {
        u = i;
        max_dis = dis;
    }
    for (auto j : adj[i]) {
        if (j.st == prt) continue;
        dfs(j.st, i, dis + j.nd);
    }
}

int dfs2(int i, int prt, int dis) {
    if (i == v) {
        min_dis = dis;
        return 0;
    }
    for (auto j : adj[i]) {
        if (j.st == prt) continue;
        int k = dfs2(j.st, i, dis + j.nd);
        if (k == -1) continue;
        k += j.nd;
        if (max(dis, k) < min_dis) {
            node = i;
            min_dis = max(dis, k);
        }
        return k;
    }

    return -1;
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    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]});
    }

    int mx = INT_MIN, max_node;

    for (int i = 0; i < N; ++i) {
        if (visited[i]) continue;
        max_dis = 0, u = i;
        dfs(i, -1, 0);
        max_dis = 0, v = u;
        dfs(v, -1, 0);
        min_dis = INT_MAX, node = u;
        dfs2(u, -1, 0);
        if (mx < min_dis) {
            mx = min_dis;
            max_node = node;
        }
        connect.push_back(node);
    }

    for (int i = 0; i < connect.size(); ++i) {
        if (connect[i] == max_node) continue;
        adj[max_node].push_back({connect[i], L});
        adj[connect[i]].push_back({max_node, L});
    }

    max_dis = 0, u = 0;
    dfs(0, -1, 0);
    max_dis = 0;
    dfs(u, -1, 0);

    return max_dis;
}

Compilation message (stderr)

dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:71:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   71 |     for (int i = 0; i < connect.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