Submission #1217125

#	Time	Username	Problem	Language	Result	Execution time	Memory
1217125		Lemser	Towns (IOI15_towns)	C++20	13 / 100	10 ms	328 KiB

towns

#include "towns.h"
#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")
#pragma GCC target("popcnt")
using namespace std;
 
using ll = long long;
using ull = unsigned long long;
using lld = long double;
using ii = pair<int,int>;
using pll = pair<ll, ll>;
 
using vi = vector<int>;
using vll = vector<ll>;
using vii = vector<ii>;
using vpll = vector<pll>;
using vlld = vector<lld>;
 
#define all(x) x.begin(),x.end()
#define lsb(x) x&(-x)
#define gcd(a,b) __gcd(a,b)
#define sz(x) (int)x.size()
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define fls cout.flush()
 
#define fore(i, l, r) for (auto i = l; i < r; i++)
#define fo(i, n) fore (i, 0, n)
#define forex(i, r, l) for (auto i = r-1; i >= l; i--)
#define ffo(i, n) forex (i, n, 0)
 
bool cmin(ll &a, ll b) { if (b < a) { a=b; return 1; } return 0; }
bool cmax(ll &a, ll b) { if (b > a) { a=b; return 1; } return 0; }

/*
getDistance (i, j)
*/

vector<int> dA, dB, dp;

bool same (ll i, ll j) { return (getDistance(i, j) == dp[i] + dp[j]); }

struct DSU {
 
    vll pa, szn;
 
    DSU () {  }
    DSU (ll n): pa(n, 0), szn(n, 1 ) { fo (i, n) pa[i] = i; }
	
	void add (ll par, ll siz) {
		pa.pb(par);
		szn.pb(siz);
	}
    ll find (ll i) { return (pa[i] == i ? i : find(pa[i])); }
    void unite (ll a, ll b) {
        ll ra = find(a), rb = find(b);
		if (ra == rb) return;
		if (szn[ra] < szn[rb]) swap(ra, rb);
		szn[ra] += szn[rb];
        pa[rb] = ra;
    }
};

// si hay un elemento mayoritario este retornara su frecuencia
ll solve (vll &vec) {
	vll alive, dead;
	DSU gr(vec.size());
	fo (i, vec.size()) alive.pb(i);
	while (alive.size() > 1) {
		vll nalive;
		for (ll i = 0; i+1 < alive.size(); i += 2) {
			if (same(vec[alive[i]], vec[alive[i+1]])) {
				gr.unite(alive[i], alive[i+1]);
				nalive.pb(alive[i]);
			} else {
				dead.pb(alive[i]);
				dead.pb(alive[i+1]);
			}
		}
		if (alive.size()&1) {
			dead.pb(alive.back());
		}
		alive = nalive;
	}
	for (ll i: dead) {
		if (same(alive[0], i)) gr.unite(alive[0], i);
	}
	return gr.szn[gr.find(alive[0])];
}

int hubDistance(int N, int sub) {
	int A = 0, B = 0, b = 0;
	fore (i, 1, N) {
		int g = getDistance (0, i);
		if (g > b) {
			b = g; 
			A = i;
		}
	}
	dA = vector<int>(N, 0);
	dB = vector<int>(N, 0);
	dp = vector<int>(N, 0);
	B = 0;
	fo (i, N) {
		if (i == A) continue;
		int g = getDistance (A, i);
		dA[i] = g;
		if (g > b) {
			b = g;
			B = i; 
		}
	}
	int ans = dA[B], ok = -1;
	fo (i, N) {
		if (i == B) continue;
		dB[i] = getDistance (B, i);
	}
	map<ll, vll> cnt;
	fo (i, N) {
		if (i == A || i == B) continue;
		int d = dA[i] + dB[i] - dA[B];
		d /= 2;
		dp[i] = d;
		cnt[dA[i] - d].pb(i);
		ans = min(ans, max(dA[i], dB[i]) - d);
	}
	ll sum = 1;
	for (auto [k, vec]: cnt) {
		ll t = vec.size();
		if (max(k, dA[B] - k) > ans) {
			sum += t;
			continue;
		}
		if (sum > N/2 || N - sum - t > N/2) {
			sum += t;
			continue;
		}
		if (t <= N/2) {
			ok = 1;
			break;
		}
		ll w = solve (vec);
		if (w <= N/2) {
			ok = 1;
			break;
		}
		sum += t;
	}
	return ans * ok; 
}

• Subtask 1: 13 / 13
• Subtask 2: 0 / 12
• Subtask 3: 0 / 13
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 39