Submission #405290

#	Time	Username	Problem	Language	Result	Execution time	Memory
405290		danielcm585	Dreaming (IOI13_dreaming)	C++14	18 / 100	57 ms	13052 KiB

dreaming

#include "dreaming.h"

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

#define fi first
#define se second

typedef pair<int,int> ii;

int ans, far;
vector<int> dis, sz;
vector<vector<ii>> adj;

void dfs(int cur, int par) {
    if (dis[cur] > dis[far]) far = cur;
    sz[cur] = 1;
    ans = max(ans,dis[cur]);
    for (auto nx : adj[cur]) {
        if (nx.fi == par) continue;
        dis[nx.fi] = dis[cur]+nx.se;
        dfs(nx.fi,cur);
        sz[cur] += sz[nx.fi];
    }
}

int centroid(int cur, int par, int sub) {
    for (auto nx : adj[cur]) {
        if (nx.fi == par) continue;
        if (sz[nx.fi]*2 > sub) return centroid(nx.fi,cur,sub);
    }
    return cur;
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    adj = vector<vector<ii>>(N);
    for (int i = 0; i < M; i++) {
        adj[A[i]].push_back(ii(B[i],T[i]));
        adj[B[i]].push_back(ii(A[i],T[i]));
    }
    dis = sz = vector<int>(N,0);
    vector<int> com;
    for (int i = 0; i < N; i++) {
        if (!sz[i]) {
            // get this component's diameter
            dis[i] = 0; far = i; dfs(i,-1);
            dis[far] = 0; dfs(far,-1);
            // get this component's centroid
            dis[i] = 0; far = i; dfs(i,-1);
            int cent = centroid(i,-1,sz[i]);
            dis[cent] = 0; far = cent; dfs(cent,-1);
            com.push_back(dis[far]);
        }
    }
    sort(com.rbegin(),com.rend());
    if (com.size() >= 2) ans = max(ans,com[0]+com[1]+L);
    if (com.size() >= 3) ans = max(ans,com[1]+com[2]+2*L);
    return ans;
}

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