Submission #623980

#	Time	Username	Problem	Language	Result	Execution time	Memory
623980		8e7	Towns (IOI15_towns)	C++17	100 / 100	16 ms	940 KiB

towns

//Challenge: Accepted
#include <bits/stdc++.h>
using namespace std;
#ifdef zisk
void debug(){cout << endl;}
template<class T, class ... U> void debug(T a, U ...b){cout << a << " ", debug(b...);}
template<class T> void pary(T l, T r) {
	while (l != r) cout << *l << " ", l++;
	cout << endl;
}
#else
#define debug(...) 0
#define pary(...) 0
#endif
#define ll long long
#define maxn 155
#define pii pair<int, int>
#define ff first
#define ss second
#include "towns.h"

int n;
int save[maxn][maxn];
bool done[maxn][maxn];
int query(int u, int v) {
	if (u == v || u >= n || v >= n) return 0;
	if (done[u][v]) return save[u][v];
	save[u][v] = save[v][u] = getDistance(u, v);
	done[u][v] = done[v][u] = 1;
	return save[u][v];
}
bool check[2*maxn];

vector<int> eq[2*maxn], dif[2*maxn];
int hubDistance(int N, int sub) {
	n = N;
	for (int i = 0;i <= n;i++) {
		for (int j = 0;j <= n;j++) done[i][j] = 0;
	}
	for (int i = 0;i <= 2*n;i++) {
		eq[i].clear();
		dif[i].clear();
		check[i] = 0;
	}
	vector<int> da, db, l(n), w(n), ws;
	int b = 0, ma = 0;
	for (int i = 0;i < n;i++) {
		da.push_back(query(0, i));	
		if (da.back() > ma) {
			ma = da.back();
			b = i;
		}
	}
	int len = ma;
	for (int i = 0;i < n;i++) {
		db.push_back(query(b, i));
		ma = max(ma, db.back());
	}
	//debug(ma);
	
	int R = 1<<30;
	for (int i = 0;i < n;i++) {
		l[i] = (da[i] + db[i] - len) / 2;	
		w[i] = db[i] - l[i];
		//debug(l[i], w[i]);
		ws.push_back(w[i]);
		R = min(R, max(w[i], ma - w[i]));
	}
	sort(ws.begin(), ws.end());
	ws.resize(int(unique(ws.begin(), ws.end()) - ws.begin()));
	int siz = ws.size();
	vector<vector<int> > col(siz, vector<int>());
	vector<int> pref(siz, 0), suf(siz, 0);
	for (int i = 0;i < n;i++) {
		int ind = lower_bound(ws.begin(), ws.end(), w[i]) - ws.begin();	
		col[ind].push_back(i);
		debug(i, ind);
	}
	for (int i = 0;i < siz;i++) pref[i] = col[i].size() + (i ? pref[i-1] : 0);	
	for (int i = siz-1;i >= 0;i--) suf[i] = col[i].size() + (i < siz-1 ? suf[i+1] : 0);

	vector<int> vec, tmp;
	for (int i = 0;i < siz;i++) {
		int v = max(ws[i], ma - ws[i]);
		if (v == R) {
			if ((i == 0 || pref[i-1] <= n/2) && (i == siz-1 || suf[i+1] <= n/2) && col[i].size() <= n/2) {
				return R;
			} else if (col[i].size() > n/2) {
				vec = col[i];
				for (int j = 0;j < n - col[i].size();j++) vec.push_back(n+j);
				break;
			}
		}
	}
	if (vec.size() == 0) return -R;
	tmp = vec;
	//pary(vec.begin(), vec.end());

	auto same = [&] (int i, int j) {
		int v = query(i, j);
		if (v == 0) return 0;
		int d = l[i] + l[j] - v;
		//debug("same", i, j, d ? 1 : 0);
		return d ? 1 : 0;
	};
	//pary(vec.begin(), vec.end());
	int surv = 0, hp = 0;
	for (int i:vec) {
		if (hp == 0) surv = i, hp = 1;
		else if (same(surv, i)) {
			eq[surv].push_back(i);
			hp++;
		} else {
			dif[surv].push_back(i);
			hp--;
		}
	}
	if (hp == 0) return R;
	int good = 1, bad = 0;
	for (int i:eq[surv]) good++, check[i] = 1;
	for (int i:dif[surv]) bad++, check[i] = 1;
	check[surv] = 1;
	
	for (int i:vec) {
		if (check[i]) continue;
		if (i == surv || same(surv, i)) {
			good++;
			for (int j:eq[i]) good++, check[j] = 1;
			for (int j:dif[i]) bad++, check[j] = 1;
		} else {
			bad++;
			for (int j:eq[i]) bad++, check[j] = 1;
		}
		if (good > n/2) return -R;
		if (bad > n/2) return R;
	}
	if (good > n/2) return -R;
	else return R;
}
/*
1 1
6
0 20 12 12 12 12
20 0 12 12 12 12
12 12 0 2 2 2
12 12 2 0 2 2
12 12 2 2 0 2
12 12 2 2 2 0

*/

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:71:19: warning: conversion from 'std::vector<int>::size_type' {aka 'long unsigned int'} to 'int' may change value [-Wconversion]
   71 |  int siz = ws.size();
      |            ~~~~~~~^~
towns.cpp:75:53: warning: conversion from '__gnu_cxx::__normal_iterator<int*, std::vector<int> >::difference_type' {aka 'long int'} to 'int' may change value [-Wconversion]
   75 |   int ind = lower_bound(ws.begin(), ws.end(), w[i]) - ws.begin();
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
towns.cpp:12:20: warning: statement has no effect [-Wunused-value]
   12 | #define debug(...) 0
      |                    ^
towns.cpp:77:3: note: in expansion of macro 'debug'
   77 |   debug(i, ind);
      |   ^~~~~
towns.cpp:79:54: warning: conversion from 'std::vector<int>::size_type' {aka 'long unsigned int'} to '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'} may change value [-Wconversion]
   79 |  for (int i = 0;i < siz;i++) pref[i] = col[i].size() + (i ? pref[i-1] : 0);
      |                                        ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
towns.cpp:80:56: warning: conversion from 'std::vector<int>::size_type' {aka 'long unsigned int'} to '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'} may change value [-Wconversion]
   80 |  for (int i = siz-1;i >= 0;i--) suf[i] = col[i].size() + (i < siz-1 ? suf[i+1] : 0);
      |                                          ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
towns.cpp:86:89: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   86 |    if ((i == 0 || pref[i-1] <= n/2) && (i == siz-1 || suf[i+1] <= n/2) && col[i].size() <= n/2) {
      |                                                                           ~~~~~~~~~~~~~~^~~~~~
towns.cpp:88:29: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   88 |    } else if (col[i].size() > n/2) {
      |               ~~~~~~~~~~~~~~^~~~~
towns.cpp:90:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   90 |     for (int j = 0;j < n - col[i].size();j++) vec.push_back(n+j);
      |                    ~~^~~~~~~~~~~~~~~~~~~
towns.cpp:35:28: warning: unused parameter 'sub' [-Wunused-parameter]
   35 | int hubDistance(int N, int sub) {
      |                        ~~~~^~~

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