Submission #830966

#	Time	Username	Problem	Language	Result	Execution time	Memory
830966		Kerim	Dreaming (IOI13_dreaming)	C++17	100 / 100	70 ms	14168 KiB

dreaming

#include "dreaming.h"
#include "bits/stdc++.h"
using namespace std;
typedef pair<int, int> pii;
const int N = 1e5+5;
vector<pii> adj[N];
vector<int> members;
bool vis[N];

void dfs0(int nd, int pr){
    vis[nd] = 1;
    members.push_back(nd);
    for (auto [to, w]: adj[nd])
        if (to != pr)
            dfs0(to, nd);
}
int max_weight, endpoint, dp[N];
void dfs(int nd, int pr, int weight){
    if (weight > max_weight){
        max_weight = weight;
        endpoint = nd;
    }
    dp[nd] = max(dp[nd], weight);
    for (auto [to, w]: adj[nd])
        if (to != pr)
            dfs(to, nd, weight+w);
}

int travelTime(int n, int m, int L, int A[], int B[], int T[]) {
    for (int i = 0; i < m; i++){
        int u = A[i], v = B[i], w = T[i];
        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
    }
    vector<int> roots;
    for (int i = 0; i < n; i++)
        if (!vis[i]){
            dfs0(i, -1);
            roots.push_back(i);
        }
    vector<int> w;
    int D = 0;
    for (auto root: roots){
        members.clear();
        dfs0(root, -1);

        max_weight = 0;
        dfs(root, -1, 0);
        int a = endpoint; 
        max_weight = 0;
        dfs(endpoint, -1, 0);
        int b = endpoint;
        D = max(D, max_weight);
        dfs(a, -1, 0);
        dfs(b, -1, 0);

        int value = INT_MAX;
        for (auto member: members)
            if (value > dp[member])
                value = dp[member];
        w.push_back(value);
    }
    sort(w.rbegin(), w.rend());
    int c = roots.size();
    int answer = D;
    if (c >= 2)
        answer = max(answer, w[0] + w[1] + L);
    if (c >= 3)
        answer = max(answer, w[1] + w[2] + 2*L);
    return answer;
}

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