Submission #88482

#	Time	Username	Problem	Language	Result	Execution time	Memory
88482		qkxwsm	Towns (IOI15_towns)	C++14	100 / 100	22 ms	800 KiB

towns

#include "towns.h"
#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/rope>

using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;

random_device(rd);
mt19937 rng(rd());
const long long FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();

struct custom_hash
{
	template<class T>
	unsigned long long operator()(T v) const
	{
		unsigned long long x = v;
		x += FIXED_RANDOM; x += 11400714819323198485ull;
		x = (x ^ (x >> 30)) * 13787848793156543929ull;
		x = (x ^ (x >> 27)) * 10723151780598845931ull;
		return x ^ (x >> 31);
	}
};

template<class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<class T, class U> using hash_table = gp_hash_table<T, U, custom_hash>;

template<class T>
void ckmin(T &a, T b)
{
	a = min(a, b);
}
template<class T>
void ckmax(T &a, T b)
{
	a = max(a, b);
}
long long expo(long long a, long long e, long long mod)
{
	return ((e == 0) ? 1 : ((expo(a * a % mod, e >> 1, mod)) * ((e & 1) ? a : 1) % mod));
}
template<class T, class U>
T nmod(T &x, U mod)
{
	if (x >= mod) x -= mod;
}
template<class T>
T gcd(T a, T b)
{
	return (b ? gcd(b, a % b) : a);
}
template<class T>
T randomize(T mod)
{
	return (uniform_int_distribution<T>(0, mod - 1))(rng);
}

#define y0 ___y0
#define y1 ___y1
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define PF push_front
#define fi first
#define se second
#define DBG(x) cerr << #x << " = " << x << endl;
#define SZ(x) ((int) (x.size()))
#define FOR(i, a, b) for (auto i = (a); i < (b); i++)
#define FORD(i, a, b) for (auto i = (a) - 1; i >= (b); i--)
#define ALL(x) x.begin(), x.end()

const long double PI = 4.0 * atan(1.0);
const long double EPS = 1e-9;

#define MAGIC 347
#define SINF 10007
#define CO 1000007
#define INF 1000000007
#define BIG 1000000931
#define LARGE 1696969696967ll
#define GIANT 2564008813937411ll
#define LLINF 2696969696969696969ll
#define MAXN 113

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pdd;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<ld> vd;
typedef vector<pii> vpi;
typedef vector<pll> vpl;
typedef vector<pdd> vpd;

int N;
int dist[MAXN][MAXN];
int U, V, D, DU, DV, L, T;
int ans;
int id[MAXN];
int lt, rt;
int maj, cnt;

int ask(int x, int y)
{
	if (x == y) return 0;
	if (dist[x][y]) return dist[x][y];
	int res = getDistance(x, y);
	dist[x][y] = res;
	dist[y][x] = res;
	return res;
}
bool check(int a, int b)
{
	//intersection of U-T to U-V
	if (id[a] < 0 || id[b] < 0)
	{
		return id[a] == id[b];
	}
	if (a == b) return true;
	return (id[a] + id[b] != ask(a, b));
}

int hubDistance(int n, int subtask)
{
	// cerr << U << ' ' << V << ' ' << D << ' ' << DU << ' ' << DV << ' ' << L << ' ' << T << endl;
	N = n; ans = 0;
	FOR(i, 0, N)
	{
		FOR(j, 0, N)
		{
			dist[i][j] = 0;
		}
		id[i] = 0;
	}
	//find a diameter!
	D = 0;
	FOR(i, 0, N)
	{
		if (ask(0, i) > D)
		{
			D = ask(0, i); U = i;
		}
	}
	D = 0;
	FOR(i, 0, N)
	{
		if (ask(U, i) > D)
		{
			D = ask(U, i); V = i;
		}
	}
	// cerr << U << ' ' << V << ' ' << D << ' ' << DU << ' ' << DV << ' ' << L << ' ' << T << endl;
	DU = (ask(0, U) - ask(0, V) + D) / 2;
	DV = (ask(0, V) - ask(0, U) + D) / 2;
	L = (ask(0, V) + ask(0, U) - D) / 2;
	ans = max(DU, DV);
	FOR(i, 0, N)
	{
		int d0 = ask(0, i), du = ask(U, i);
		if (d0 - du <= L - DU) continue;
		int da = (du + DU - d0 + L) / 2;
		ckmin(ans, max(da, D - da));
	}
	// cerr << DU << ' ' << DV << ' ' << L << ' ' << ans << endl;
	lt = -1; rt = -1;
	if (DU == ans) rt = 0;
	if (DV == ans) lt = 0;
	FOR(i, 0, N)
	{
		int d0 = ask(0, i), du = ask(U, i);
		if (d0 - du <= L - DU) continue;
		int da = (du + DU - d0 + L) / 2;
		if (da == ans) rt = i;
		if (D - da == ans) lt = i;
	}
	if (lt == rt) rt = -1;
	if (lt != -1 && rt != -1)
	{
		int lts = 0, rts = 0;
		FOR(i, 0, N)
		{
			int d0 = ask(0, i), du = ask(U, i);
			if (d0 - du <= L - DU)
			{
				rts++;
			}
			else
			{
				int da = (du + DU - d0 + L) / 2;
				if (da <= D - ans) lts++;
				else rts++;
			}
		}
		if (lts == rts) return ans;
		if (lts > rts) rt = -1;
		else lt = -1;
	}
	// DBG(lt); DBG(rt);
	T = ((lt == -1) ? rt : lt);
	//you're trying to see if the one @T will be good
	DV = (ask(T, U) - ask(T, V) + D) / 2;
	FOR(i, 0, N)
	{
		int d0 = ask(0, i), du = ask(U, i);
		if (d0 - du <= L - DU) continue;
		int da = (du + DU - d0 + L) / 2;
		if (da < DV) id[i] = -1;
	}
	FOR(i, 0, N)
	{
		if (id[i] == -1) continue;
		id[i] = ask(U, i) - DV;
	}
	// FOR(i, 0, N)
	// {
	// 	cerr << id[i] << ' ';
	// }
	// cerr << endl;
	//lol...
	// DBG(T);
	vi bucket, lis;
	FOR(i, 0, N)
	{
		if (!lis.empty() && check(lis.back(), i))
		{
			bucket.PB(i);
			continue;
		}
		else
		{
			lis.PB(i);
			if (!bucket.empty())
			{
				lis.PB(bucket.back());
				bucket.pop_back();
			}
		}
	}
	if (bucket.empty()) return ans;
	//any two adjacent elements in lis are different!
	while(!bucket.empty() && !lis.empty())
	{
		int x = lis.back(); T = bucket.back();
		if (check(x, T))
		{
			lis.pop_back();
			if (!lis.empty()) lis.pop_back();
		}
		else
		{
			lis.pop_back();
			bucket.pop_back();
		}
	}
	if (bucket.empty())
	{
		return ans;
	}
	else
	{
		return -ans;
	}
	// return ((cnt * 2 > N) ? -ans : ans);
}

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:128:28: warning: unused parameter 'subtask' [-Wunused-parameter]
 int hubDistance(int n, int subtask)
                            ^~~~~~~

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