Submission #366587

#	Time	Username	Problem	Language	Result	Execution time	Memory
366587		VEGAnn	Papričice (COCI20_papricice)	C++14	110 / 110	316 ms	28396 KiB

papricice

#include <bits/stdc++.h>
#define PB push_back
#define sz(x) ((int)x.size())
using namespace std;
const int N = 200100;
const int oo = 2e9;
multiset<int> A, B;
multiset<int>::iterator itr;
vector<int> g[N];
int n, siz[N], ans = oo;

void calc_siz(int v, int p){
    siz[v] = 1;

    for (int u : g[v]){
        if (u == p) continue;

        calc_siz(u, v);

        siz[v] += siz[u];
    }
}

void upd(int x, int y, int z){
    ans = min(ans, max(max(abs(x - y), abs(y - z)), abs(z - x)));
}

void dfs(int v, int p){
    if (v > 0) {
        if (sz(A) > 0){
            itr = A.upper_bound((n + siz[v]) / 2);

            if (itr != A.end()){
                int cur = (*itr);

                upd(siz[v], cur - siz[v], n - cur);
            }

            if (itr != A.begin()){
                int cur = (*prev(itr));

                upd(siz[v], cur - siz[v], n - cur);
            }
        }

        if (sz(B) > 0){
            itr = B.upper_bound((n - siz[v]) / 2);

            if (itr != B.end()){
                int cur = (*itr);

                upd(siz[v], cur, n - cur - siz[v]);
            }

            if (itr != B.begin()){
                int cur = (*prev(itr));

                upd(siz[v], cur, n - cur - siz[v]);
            }
        }

        A.insert(siz[v]);
    }

    for (int u : g[v]){
        if (u == p) continue;

        dfs(u, v);
    }

    if (v > 0){
        A.erase(A.find(siz[v]));
        B.insert(siz[v]);
    }
}

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

#ifdef _LOCAL
    freopen("in.txt","r",stdin);
#endif // _LOCAL

    cin >> n;

    for (int i = 1; i < n; i++){
        int x, y; cin >> x >> y; x--; y--;

        g[x].PB(y);
        g[y].PB(x);
    }

    calc_siz(0, -1);
    dfs(0, -1);

    cout << ans;

    return 0;
}

• Subtask 1: 15 / 15
• Subtask 2: 35 / 35
• Subtask 3: 60 / 60