Submission #541276

#	Time	Username	Problem	Language	Result	Execution time	Memory
541276		Victor	Parkovi (COCI22_parkovi)	C++17	40 / 110	3088 ms	49104 KiB

Main

// #pragma GCC target ("avx,avx2,fma")
// #pragma GCC optimize ("Ofast,inline") // O1 - O2 - O3 - Os - Ofast
// #pragma GCC optimize ("unroll-loops")
#include <bits/stdc++.h>

using namespace std;

#define rep(i, a, b) for (int i = (a); i < (b); ++i)
#define per(i, a, b) for (int i = (b - 1); i >= (a); --i)
#define trav(a, x) for (auto &a : x)

#define all(x) x.begin(), x.end()
#define sz(x) x.size()
#define pb push_back
#define debug(x) cout << #x << " = " << x << endl

#define umap unordered_map
#define uset unordered_set

typedef pair<int, int> ii;
typedef pair<int, ii> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vi> vvi;

typedef long long ll;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
typedef vector<pll> vpll;

const int INF = 1'000'000'007;

int k, n;
vpll graph[200005];
ll mid, max_dist[200005], to_park[200005], need[200005];
uset<ll> ans;

void dfs(ll u, ll p) {
    max_dist[u] = 0;
    to_park[u] = ll(1e16);
    need[u] = 0;

    trav(edge, graph[u]) {
        ll v, w;
        tie(v, w) = edge;
        if (v != p) {
            dfs(v, u);

            need[u] += need[v];

            max_dist[v] += w;
            to_park[v] += w;

            if (max_dist[v] > mid) {
                max_dist[v] = -1e16;
                to_park[v] = w;
                ++need[u];
                //cout << "u = " << u + 1 << " v = " << v + 1 << endl;
                ans.insert(v);
            }

            // cout<<max_dist[u]<<" "<<to_park[u]<<" "<<max_dist[v]<<" "<<to_park[v]<<endl;
            if (max_dist[u] + to_park[v] <= mid) max_dist[u] = ll(-1e16);
            if (max_dist[v] + to_park[u] > mid && max_dist[v] > max_dist[u]) max_dist[u] = max_dist[v];
            if (to_park[v] < to_park[u]) to_park[u] = to_park[v];
        }
    }

    if (!u && to_park[u] > mid) {
        ++need[u];
        ans.insert(u);
    }

    //cout << "u = " << u + 1 << " p = " << p + 1 << " max_dist = " << max_dist[u] << " to_park = " << to_park[u] << endl;
    //cout << "ans = " << need[u] << endl << endl;
}

ll dists[200005];
void dfs2(int u, int p) {
    if (ans.count(u)) dists[u] = 0;
    trav(edge, graph[u]) {
        ll v, w;
        tie(v, w) = edge;
        if (v != p) {
            dfs2(v, u);
            dists[u]=min(dists[u],dists[v]+w);
        }
    }
}

void dfs3(int u,int p) {
    trav(edge, graph[u]) {
        ll v, w;
        tie(v, w) = edge;
        if (v != p) {
            dists[v]=min(dists[v],dists[u]+w);
            dfs3(v, u);
        }
    }
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);

    cin >> n >> k;
    rep(i, 1, n) {
        int u, v, w;
        cin >> u >> v >> w;
        graph[--u].emplace_back(--v, w);
        graph[v].emplace_back(u, w);
    }

    ll lo = 0, hi = ll(1e15);
    while (lo != hi) {
        mid = (lo + hi) / 2;
        dfs(0, 0);

        fill(dists, dists + 200005, ll(1e15));
        dfs2(0,0);
        dfs3(0,0);

        ll max_dist = 0;
        rep(i, 0, n) {
            max_dist = max(max_dist, dists[i]);
        }

        if (max_dist > mid) ans.insert(0);

        if (sz(ans) <= k)
            hi = mid;
        else
            lo = mid + 1;
        //debug(sz(ans));
        //cout << endl;
        ans.clear();
    }

    mid = lo;
    dfs(0, 0);
    fill(dists, dists + 200005, ll(1e16));
    trav(val, ans) ans.insert(val);
    dfs2(0,0);
    dfs3(0,0);

    ll max_dist = 0;
    rep(i, 0, n) max_dist = max(max_dist, dists[i]);
    // debug(max_dist);

    if (max_dist > mid) ans.insert(0);

    rep(i, 0, n) {
        if (sz(ans) == k) break;
        ans.insert(i);
    }

    cout << mid << endl;
    trav(val, ans) cout << val + 1 << ' ';
    cout << endl;
    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:130:21: warning: comparison of integer expressions of different signedness: 'std::unordered_set<long long int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  130 |         if (sz(ans) <= k)
      |                     ^
Main.cpp:153:21: warning: comparison of integer expressions of different signedness: 'std::unordered_set<long long int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  153 |         if (sz(ans) == k) break;
      |                     ^

• Subtask 1: 10 / 10
• Subtask 2: 0 / 10
• Subtask 3: 30 / 30
• Subtask 4: 0 / 60