Submission #1173000

#	Time	Username	Problem	Language	Result	Execution time	Memory
1173000		InvMOD	Parkovi (COCI22_parkovi)	C++20	110 / 110	871 ms	44576 KiB

Main

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

#define fi first
#define se second
#define gcd __gcd
#define sz(v) (int) v.size()
#define pb push_back
#define pi pair<int,int>
#define all(v) (v).begin(), (v).end()
#define compact(v) (v).erase(unique(all(v)), (v).end())
#define FOR(i, a, b) for(int i = (a); i <= (b); i++)
#define REV(i, a, b) for(int i = (a); i >= (b); i--)
#define dbg(x) "[" #x " = " << (x) << "]"
///#define int long long

using ll = long long;
using ld = long double;
using ull = unsigned long long;

template<typename T> bool ckmx(T& a, const T& b){if(a < b) return a = b, true; return false;}
template<typename T> bool ckmn(T& a, const T& b){if(a > b) return a = b, true; return false;}

const int N = 2e5+5;
const ll MOD = 1e9+7;
const ll INF = 1e18;


struct Edge{
    int u,v,w;
    Edge(int u = 0, int v = 0, int w = 0): u(u), v(v), w(w) {}
};

void solve()
{
    int n,k; cin >> n >> k;

    vector<Edge> E(n);
    for(int i = 1; i < n; i++){
        int u,v,w; cin >> u >> v >> w;
        E[i] = Edge(u, v, w);
    }

    vector<vector<int>> adj(n + 1, vector<int>());
    for(int i = 1; i < n; i++){
        int u = E[i].u, v = E[i].v;
        adj[u].push_back(i);
        adj[v].push_back(i);
    }

    vector<bool> choosed(n + 1, false);
    auto check = [&](ll MxDist) -> bool{
        int cntPark = 0;

        vector<ll> noPark(n + 1), nearPark(n + 1, INF);
        // noPark[x]: farthest dist inside subtree x that has no park / can't go to any park
        // nearPark[x]: nearest park inside subtree x and nearest to x

        function<void(int,int)> calc_dp = [&](int x, int idE) -> void{
            choosed[x] = false;

            for(int id : adj[x]){
                int v = E[id].u ^ E[id].v ^ x; ll w = E[id].w;
                if(id != idE){
                    calc_dp(v, id);

                    nearPark[x] = min(nearPark[x], nearPark[v] + w);
                }
            }

            if(nearPark[x] + noPark[x] > MxDist){
                // we will have to choose park from parent else we will choose inside our subtree
                if(idE < 0){
                    // no parent to choose so we have to choose x
                    choosed[x] = true;
                    nearPark[x] = 0;
                }
                else{
                    int p = E[idE].u ^ E[idE].v ^ x;
                    if(noPark[x] + 1ll * E[idE].w <= MxDist){
                        // we can keep noPark to parent
                        noPark[p] = max(noPark[p], noPark[x] + 1ll * E[idE].w);
                    }
                    else{
                        // we can't keep it so we have to choose it
                        choosed[x] = true;
                        nearPark[x] = 0;
                    }
                }
            }
            cntPark += choosed[x];
            return;
        };

        calc_dp(1, -1);

        return cntPark <= k;
    };

    ll l = 0, r = 1e15;
    while(l + 1 < r){
        ll m = l+r>>1;

        if(check(m)){
            r = m;
        }
        else l = m;
    }

    check(r);

    cout << r << "\n";

    int cntUsed = 0;
    for(int i = 1; i <= n; i++){
        if(choosed[i]){
            cout << i << " ";
            cntUsed++;
        }
    }

    for(int i = 1; i <= n; i++){
        if(cntUsed >= k) break;
        if(!choosed[i]){
            cout << i <<" ";
            cntUsed++;
        }
    }
    cout << "\n";
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    #define name "InvMOD"
    if(fopen(name".INP", "r")){
        freopen(name".INP","r",stdin);
        freopen(name".OUT","w",stdout);
    }

    int t = 1; //cin >> t;
    while(t--) solve();
    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:140:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  140 |         freopen(name".INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
Main.cpp:141:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  141 |         freopen(name".OUT","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

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