Submission #646798

#	Time	Username	Problem	Language	Result	Execution time	Memory
646798		BackNoob	Papričice (COCI20_papricice)	C++14	110 / 110	264 ms	37328 KiB

papricice

#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define endl '\n'
#define MASK(i) (1LL << (i))
#define ull unsigned long long
#define ld long double
#define pb push_back
#define all(x) (x).begin() , (x).end()
#define BIT(x , i) ((x >> (i)) & 1)
#define TASK "task"
#define sz(s) (int) (s).size()
 
using namespace std;
const int mxN = 5e5 + 227;
const int inf = 1e9 + 277;
const int mod = 1e9 + 7;
const ll infll = 1e18 + 7;
const int base = 307;
const int LOG = 20;
 
template <typename T1, typename T2> bool minimize(T1 &a, T2 b) {
    if (a > b) {a = b; return true;} return false;
}
template <typename T1, typename T2> bool maximize(T1 &a, T2 b) {
    if (a < b) {a = b; return true;} return false;
}
 
int n;
int sub[mxN];
vector<int> adj[mxN];
multiset<int> ms1;
multiset<int> ms2;
int res = inf;

void dfs_pre(int u, int p)
{
    sub[u] = 1;
    for(int v : adj[u]) {
        if(v == p) continue;
        dfs_pre(v, u);
        sub[u] += sub[v];
    }
}

void dfs(int u, int p)
{
    if(sz(ms1) > 0) {
        for(int d = -1; d <= 1; d++) {
            int x = (sub[u] + n + d) / 2;
            auto it = ms1.lower_bound(x);
            if(it != ms1.end()) {
                minimize(res, max({sub[u], *it - sub[u], n - *it}) - min({sub[u], *it - sub[u], n - *it}));
            }
            if(it != ms1.begin()) {
                --it;
                minimize(res, max({sub[u], *it - sub[u], n - *it}) - min({sub[u], *it - sub[u], n - *it}));            
            }
        }
    }
    if(sz(ms2) > 0) {
        for(int d = -1; d <= 1; d++) {
            int x = (n - sub[u] + d) / 2;
            auto it = ms2.lower_bound(x);
            if(it != ms2.end()) {
                minimize(res, max({sub[u], *it , n - *it - sub[u]}) - min({sub[u], *it, n - *it - sub[u]}));
            }
            if(it != ms2.begin()) {
                --it;
                minimize(res, max({sub[u], *it , n - *it - sub[u]}) - min({sub[u], *it, n - *it - sub[u]}));
            }
        }
    }

    ms1.insert(sub[u]);
    for(int v : adj[u]) {
        if(v == p) continue;
        dfs(v, u);
    }

    ms1.erase(ms1.find(sub[u]));
    ms2.insert(sub[u]);
}

void solve()
{
    cin >> n;
    for(int i = 1; i < n; i++) {
        int u, v;
        cin >> u >> v;
        adj[u].pb(v);
        adj[v].pb(u);
    }

    dfs_pre(1, -1);
    dfs(1, -1);

    cout << res;
}
 
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

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

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