Submission #318340

#	Time	Username	Problem	Language	Result	Execution time	Memory
318340		nkft	Papričice (COCI20_papricice)	C++17	110 / 110	358 ms	29412 KiB

papricice

#include "bits/stdc++.h"
using namespace std;
#define int long long
#define mp make_pair
#define pb push_back
#define pf push_front
#define fi first
#define se second
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define nbits(x) __builtin_popcount(x)
#define gcd(x, y) __gcd(x, y)
#define SYNC_OFF ios::sync_with_stdio(0); cin.tie(0);
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<pii> vii;  
const int MOD = 1e9 + 7; // 998244353;
const int N = 200100;
const int INF = 1e15; // 1e18;
const double PI = acos(-1);
const int dx[] = {-1,0,1,0,-1,1,1,-1};
const int dy[] = {0,1,0,-1,1,1,-1,-1};
int powmod(int a, int b, int m = MOD) {
    int res = 1;
    a %= m; assert(b >= 0);
    for (; b; b>>=1) {
        if (b & 1) res = res*a % m;
        a = a*a % m;
    }
    return res;
}

int n;
int sz[N];
vector<int> g[N];
multiset<int> A, B;

int dfs(int x, int p) {
    sz[x] = 1;
    for (int y: g[x]) {
        if (y != p) {
            sz[x] += dfs(y, x);
        }
    }
    return sz[x];
}

vector<int> cand(multiset<int>& S, int k) {
    vector<int> res;
    auto ub = S.upper_bound(k);
    if (ub != S.end()) {
        res.pb(*ub);
    }
    auto lb = S.lower_bound(k);
    if (lb != S.end()) {
        res.pb(*lb);
    }
    if (lb != S.begin()) {
        res.pb(*prev(lb));
    }
    return res;
}

int solve(int x, int p) {
    int ans = INF;
    for (int szy: cand(A, (n + sz[x]) / 2)) {
        int res = max({sz[x], szy - sz[x], n - szy});
        res -= min({sz[x], szy - sz[x], n - szy});
        ans = min(ans, res);
    }
    for (int szy: cand(B, (n - sz[x]) / 2)) {
        int res = max({sz[x], szy, n - sz[x] - szy});
        res -= min({sz[x], szy, n - sz[x] - szy});
        ans = min(ans, res);
    }
    A.insert(sz[x]);
    for (int y: g[x]) {
        if (y != p) {
            ans = min(ans, solve(y, x));
        }
    }
    A.erase(A.find(sz[x]));
    B.insert(sz[x]);
    return ans;
}

signed main() {
    SYNC_OFF;
    cin >> n;
    for (int i = 1; i <= n - 1; i++) {
        int u, v; cin >> u >> v;
        g[u].pb(v); g[v].pb(u);
    }
    dfs(1, 0);
    cout << solve(1, 0) << "\n";
    return 0;
}

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