Submission #846128

#	Time	Username	Problem	Language	Result	Execution time	Memory
846128		detaomega	Dreaming (IOI13_dreaming)	C++14	0 / 100	17 ms	4440 KiB

dreaming

#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>

using namespace std;
#include "dreaming.h"

const int maxn = 1e4 + 5;

vector<pair<int,int>> G[maxn];
vector<int> vis(maxn, 0);
vector<int> dp(maxn, 0);
int getDiameter(int n) {
    queue<int> q;
    vector<int> dis(maxn, -1);
    q.push(1);
    dis[1] = 0;
    while (q.size()) {
        int u = q.front();
        q.pop();
        for (auto e : G[u]) {
            int v = e.first;
            if (dis[v] == -1) {
                dis[v] = dis[u] + e.second;
                q.push(v);
            }
        }
    }
    int now = 0, mx = 0;
    for (int i = 1; i <= n; i++) {
        if (mx < dis[i]) {
            mx = dis[i];
            now = i;
        }
        dis[i] = -1;
    }
    q.push(now);
    dis[now] = 0;
    while (q.size()) {
        int u = q.front();
        q.pop();
        for (auto e : G[u]) {
            int v = e.first;
            if (dis[v] == -1) {
                dis[v] = dis[u] + e.second;
                q.push(v);
            }
        }
    }
    return *max_element(dis.begin(), dis.end());
}

int dfs(int now, int fa) {
    int mx = 0;
    for (auto e : G[now]) {
        if (e.first != fa) {
            mx = max(mx, dfs(e.first, now) + e.second);
        }
    }
    return mx;
}

int dfs1(int now, int fa) {
    int mx = dp[now];
    vis[now] = true;
    for (auto e : G[now]) {
        if (e.first != fa) {
            mx = min(dfs1(e.first, now), mx);
        }
    }
    return mx;
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    for (int i = 0; i < M; i++) {
        // cout << A[i] << " " << B[i];
        A[i]++;
        B[i]++;
        G[A[i]].emplace_back(B[i], T[i]);
        G[B[i]].emplace_back(A[i], T[i]);
    }

    if (N == 1) {
        return 0;
    }
    if (N == M + 1) {
        return getDiameter(N);
    }
    if (N == 2) {
        return L;
    }
    if (M == 0) {
        return L * 2;
    }
    
    for (int i = 1; i <= N; i++) {
        dp[i] = dfs(i, 0);
    }
    
    int ans = 0;
    for (int i = 1; i <= N; i++) {
        if (!vis[i]) {
            cout << i - 1 << " " << dfs1(i, 0) << "\n"; 
            ans = ans + dfs1(i, 0);
        }
    }
    return ans + L;
}

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