제출 #829216

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
829216		vjudge1	꿈 (IOI13_dreaming)	C++17	0 / 100	47 ms	36328 KiB

dreaming

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

// Problem
// Given a tree with M edge, make new edge with weight = L such that for every pair of nodes, the maxmimum weight path is minimum
// How?
// Maximum path = tree diameter?
// The goal is to minimize the overall tree diameter

const int MAXN = 1e6;
vector<pair<int, int>> adj[MAXN];
bool vis[MAXN];
pair<int, int> mmb[MAXN];
int bmg[MAXN];
int dep[MAXN];

void DFS(int u, int p)
{
    vis[u] = 1;
    mmb[u] = {0, u};
    for (auto &[v, w] : adj[u])
    {
        if (v == p)
            continue;
        DFS(v, u);
        mmb[u] = max(mmb[u], make_pair(mmb[v].first + w, mmb[v].second));
    }
}

int DDFS(int u, int p)
{
    bmg[u] = max(bmg[u], dep[u]);
    int ans = bmg[u];
    for (auto &[v, w] : adj[u])
    {
        if (v == p)
            continue;
        dep[v] = dep[u] + w;
        ans = min(ans, DDFS(v, u));
    }
    return ans;
}

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(make_pair(B[i], T[i]));
        adj[B[i]].push_back(make_pair(A[i], T[i]));
    }
    int ans = 0;
    vector<int> dias;
    for (int i = 0; i < N; i++)
    {
        if (!vis[i])
        {
            DFS(i, -1);
            int x = mmb[i].second;
            int y = mmb[x].second;
            DDFS(x, -1);
            ans = max(ans, mmb[x].first);
            dep[x] = 0;
            DDFS(x, -1);
            dep[y] = 0;
            dias.push_back(DDFS(y, -1));
        }
    }
    sort(dias.rbegin(), dias.rend());
    if ((int)dias.size() >= 2)
    {
        ans = max(ans, dias[0] + dias[1] + L);
    }
    if ((int)dias.size() >= 3)
    {
        ans = max(ans, dias[1] + dias[2] + L * 2);
    }
    return ans;
}

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