Submission #788738

#	Time	Username	Problem	Language	Result	Execution time	Memory
788738		hafo	Parkovi (COCI22_parkovi)	C++14	110 / 110	938 ms	35288 KiB

Main

#include <bits/stdc++.h>
#define ll long long
#define ull unsigned ll
#define pb push_back
#define pa pair<int, int>
#define pall pair<ll, int>
#define fi first
#define se second
#define TASK "test"
#define Size(x) (int) x.size()
#define all(x) x.begin(), x.end()
using namespace std;

template<typename T1, typename T2> bool mini (T1 &a, T2 b) {if(a > b) a = b; else return 0; return 1;}
template<typename T1, typename T2> bool maxi (T1 &a, T2 b) {if(a < b) a = b; else return 0; return 1;}

const int MOD = 1e9 + 7;
const int LOG = 20;
const int maxn = 2e5 + 7;
const ll oo = 1e18 + 69;

int n, k, u, v, w, cnt = 0;
vector<pa> g[maxn];
bool placed[maxn];
ll dist[maxn], reach[maxn];

void dfs(int u, int par, ll lim) {
    dist[u] = oo;
    reach[u] = 0;

    for(auto e:g[u]) {
        int v = e.fi, w = e.se;
        if(v == par) continue;
        dfs(v, u, lim);

        if(reach[v] + min(1LL * w, dist[v]) <= lim) {
            placed[v] = 0;
            if(reach[v] + dist[v] > lim) {
                maxi(reach[u], reach[v] + w);
            }
            mini(dist[u], dist[v] + w);
        } else {
            placed[v] = 1;
            cnt++;
            mini(dist[u], w);
        }
    } 
}

bool check(ll lim) {
    cnt = 0;
    dfs(1, 0, lim);
    if(reach[1] + dist[1] <= lim) placed[1] = 0;
    else {
        placed[1] = 1;
        cnt++;
    }
    return cnt <= k;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    //freopen(TASK".inp", "r", stdin);
    //freopen(TASK".out", "w", stdout);

    cin>>n>>k;
    for(int i = 1; i < n; i++) {
        cin>>u>>v>>w;
        g[u].pb({v, w});
        g[v].pb({u, w});
    }

    ll l = 0, r = 1e15, mid, res;
    while(l <= r) {
        mid = l + r >> 1;
        if(check(mid)) {
            res = mid;
            r = mid - 1;
        } else l = mid + 1;
    }

    cout<<res<<"\n";
    vector<int> ans;
    check(res);
    for(int i = 1; i <= n; i++) 
        if(placed[i]) ans.pb(i);
    for(int i = 1; i <= n; i++) 
        if(Size(ans) < k && !placed[i]) ans.pb(i);
    for(auto i:ans) cout<<i<<" ";
    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:77:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   77 |         mid = l + r >> 1;
      |               ~~^~~
Main.cpp:86:10: warning: 'res' may be used uninitialized in this function [-Wmaybe-uninitialized]
   86 |     check(res);
      |     ~~~~~^~~~~

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