Submission #967229

#	Time	Username	Problem	Language	Result	Execution time	Memory
967229		VMaksimoski008	Dreaming (IOI13_dreaming)	C++14	100 / 100	60 ms	15816 KiB

dreaming

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

using ll = long long;
using pii = pair<int, int>;
const int maxn = 1e5 + 5;

int n, m, l;
ll val, mx, D;
vector<pii> graph[maxn];
vector<bool> vis(maxn);
vector<ll> dist(maxn), dist2(maxn);
vector<int> seen;

void dfs(int u, int p, bool t) {
    vis[u] = 1;
    if(dist[u] > val) val = dist[u], mx = u;
    if(t) seen.push_back(u);
    D = max(D, dist[u]);
    for(auto &[v, w] : graph[u]) {
        if(v == p) continue;
        dist[v] = dist[u] + w;
        dfs(v, u, t);
    }
}

void dfs2(int u, int p) {
    for(auto &[v, w] : graph[u]) {
        if(v == p) continue;
        dist2[v] = dist2[u] + w;
        dfs2(v, u);
    }
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    n = N, m = M, l = L;
    ll ans = 0;

    for(int i=0; i<m; i++) {
        graph[A[i]].push_back({ B[i], T[i] });
        graph[B[i]].push_back({ A[i], T[i] });
    }

    vector<pair<ll, int> > v;

    for(int i=0; i<n; i++) {
        if(vis[i]) continue;
        seen.clear();
        mx=i, val=0;
        dfs(i, i, 0);
        D = 0;
        dist[mx] = 0;
        dfs(mx, mx, 1);

        int U = mx, V = U;
        for(int &x : seen)
            if(dist[x] > dist[V]) V = x;

        dfs2(V, V);
        ll val=1e18, curr=0;

        for(int &x : seen) {
            if(max(dist[x], dist2[x]) < val) {
                val = max(dist[x], dist2[x]);
                curr = x;
            }
        }

        v.push_back({ val, curr });
        ans = max(ans, D);
    }

    sort(v.begin(), v.end());
    reverse(v.begin(), v.end());
    
    if(v.size() > 1) {
        ans = max(ans, v[0].first + v[1].first + l);
        if(v.size() > 2) ans = max(ans, v[1].first + v[2].first + 2 * l);
    }

    return ans;
}

Compilation message (stderr)

dreaming.cpp: In function 'void dfs(int, int, bool)':
dreaming.cpp:21:15: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   21 |     for(auto &[v, w] : graph[u]) {
      |               ^
dreaming.cpp: In function 'void dfs2(int, int)':
dreaming.cpp:29:15: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   29 |     for(auto &[v, w] : graph[u]) {
      |               ^

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