Submission #119859

#	Time	Username	Problem	Language	Result	Execution time	Memory
119859		WhipppedCream	Towns (IOI15_towns)	C++17	35 / 100	65 ms	968 KiB

towns

#include "towns.h"
#include <bits/stdc++.h>
#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
using namespace std;
#define X first
#define Y second
#define pb push_back
typedef pair<int, int> ii;
typedef long long ll;

const int maxn = 120;

int m, n;

int dist0[maxn];
int distu[maxn];
int add[maxn], bran[maxn];

map<int, int> cnt;
map<int, vector<int> > faker;
map<int, int> on;

int hub;

bool isSame(int u, int v)
{
	if(u == -1 || v == -1) return false;
	return getDistance(u, v) != distu[u]+distu[v]-2*hub;
}

vector<int> gon;
vector<int> buck;

void proc(int x)
{
	if(gon.empty() || !isSame(gon.back(), x))
	{
		gon.push_back(x);
		if(!buck.empty())
		{
			gon.pb(buck.back());
			buck.pop_back();
		}
	}
	else
	{
		buck.pb(x);
	}
}

int hubDistance(int N, int sub)
{
	gon.clear();
	buck.clear();
	memset(add, 0, sizeof add);
	memset(bran, 0, sizeof bran);
	cnt.clear();
	faker.clear();
	on.clear();
	n = N;
	int best = 0, dat = -1;
	for(int i = 1; i< N; i++)
	{
		dist0[i] = getDistance(0, i);
		if(dist0[i]> best)
		{
			best = dist0[i];
			dat = i;
		}
	}
	int U = dat;
	best = 0; dat = -1;
	for(int i = 0; i< N; i++)
	{
		if(i == U) continue;
		if(i == 0)
		{
			distu[0] = dist0[U];
		}
		distu[i] = getDistance(U, i);
		if(distu[i]> best)
		{
			best = distu[i];
			dat = i;
		}
	}
	int V = dat;
	int diam = distu[V];
	// printf("(%d->%d) %d\n", U, V, dist[V]);
	distu[0] = dist0[U];
	for(int i = 0; i< N; i++)
	{
		if(i == U || i == 0) continue;
		int br = dist0[i]+distu[i]-dist0[U];
		br /= 2;
		int pos = distu[i]-br;
		add[i] = pos;
		bran[i] = br;
		cnt[pos]++;
		faker[pos].pb(i);
	}
	int rad = diam;
	bool good = false;
	int cm = 1;
	for(auto kk : cnt)
	{
		int x = kk.X;
		rad = min(rad, max(x, diam-x));
	}
	if(sub == 2) return rad;
	vector<int> hubs;
	for(auto kk : cnt)
	{
		int x = kk.X, y = kk.Y;
		if(rad == max(x, diam-x))
		{
			hubs.pb(x);
			if(max(max(cm, cnt[x]), n-cm-cnt[x]) <= n/2) good = true;
		}
		cm += cnt[x];
		on[x] = cm;
	}
	vector<int> doubt;
	while(!hubs.empty())
	{
		int u = hubs.back(); hubs.pop_back();
		if(max(on[u]-cnt[u], n-on[u])> n/2) continue;
		if(max(cnt[u], max(on[u]-cnt[u], n-on[u]))<= n/2) return rad;
		doubt.pb(u);
	}
	if(doubt.empty()) return -rad;
	hub = doubt[0];
	int tweet = n-cnt[hub];
	while(tweet--) proc(-1);
	for(int i = 0; i< (int) faker[hub].size(); i++) proc(faker[hub][i]);
	int T = gon.back(); gon.pop_back();
	while(!gon.empty())
	{
		int S = gon.back();
		if(isSame(S, T)) 
		{
			if(gon.size() == 1) 
			{
				buck.pb(gon[0]); gon.pop_back();
			}
			else
			{
				gon.pop_back(); gon.pop_back();
			}
		}
		else
		{
			gon.pop_back(); 
			if(buck.empty()) return rad;
			buck.pop_back();
		}
	}
	if(buck.empty()) return rad;
	return -rad;
}

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:115:17: warning: unused variable 'y' [-Wunused-variable]
   int x = kk.X, y = kk.Y;
                 ^
towns.cpp:104:7: warning: variable 'good' set but not used [-Wunused-but-set-variable]
  bool good = false;
       ^~~~

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