Submission #790233

#	Time	Username	Problem	Language	Result	Execution time	Memory
790233		ymm	Towns (IOI15_towns)	C++17	61 / 100	955 ms	888 KiB

towns

#include "towns.h"
#include <bits/stdc++.h>
#define Loop(x,l,r) for (ll x = (l); x < (r); ++x)
#define LoopR(x,l,r) for (ll x = (r)-1; x >= (l); --x)
typedef std::pair<int,int> pii;
typedef long long ll;
using namespace std;
 
const int N = 120;
int dis0[N], disa[N];//, disb[N];
 
int dis[N][N];
int cnt;
 
namespace dsu {
	int par[N];
	int sz[N];
	void init() {
		fill(par, par+N, -1);
		fill(sz, sz+N, 1);
	}
	int rt(int v) { return par[v] == -1? v: (par[v] = rt(par[v])); }
	void unite(int v, int u) {
		//v = rt(v);
		//u = rt(u);
		//if (sz[v] < sz[u])
		//	swap(v, u);
		sz[v] += sz[u];
		par[u] = v;
	}
}
 
int get(int i, int j)
{
	if (i == j)
		return 0;
	if (i > j)
		swap(i, j);
	if (!dis[i][j]) {
		++cnt;
		dis[i][j] = getDistance(i, j);
	}
	return dis[i][j];
}
 
int get2(int a, int v, int b)
{
	return (get(a, v) + get(a, b) - get(v, b))/2;
}
 
int find_hub(int a, int b, int n, int r)
{
	if (get(a, b) == r*2)
		return r;
	bool x = 0, y = 0;
	vector<int> X, Y;
	Loop (i,0,n) {
		if (get2(a, i, 0) == r)
			x = 1;
		if (get2(a, i, 0) == get(a, b) - r)
			y = 1;
		int x = get2(a, i, 0);
		int y = get(a, b) - x;
		(x < y? Y: X).push_back(i);
	}
	if (!x)
		return get(a, b) - r;
	if (!y)
		return r;
	if (X.size()*2 > n)
		return r;
	if (X.size()*2 == n)
		return -1;
	return get(a, b) - r;
}
 
mt19937_64 rd(time(0));
int sel(const vector<int> &val)
{
	int sum = accumulate(val.begin(), val.end(), 0);
	int x = rd() % sum;
	Loop (i,0,val.size()) {
		if (x < val[i])
			return i;
		x -= val[i];
	}
	assert(false);
}
 
int hubDistance(int n, int sub) {
	memset(dis, 0, sizeof(dis));
	cnt = 0;
	Loop (i,0,n)
		dis0[i] = get(0, i);
	int a = max_element(dis0, dis0+n) - dis0;
	Loop (i,0,n)
		disa[i] = get(a, i);
	int b = max_element(disa, disa+n) - disa;
	//Loop (i,0,n)
	//	disb[i] = get(b, i);
	int ans = 1e9;
	Loop (i,0,n) {
		int x = get2(a, i, 0);
		int y = disa[b] - x;
		ans = min(ans, max(x, y));
	}
	int v = find_hub(a, b, n, ans);
	if (v == -1)
		return ans;
	vector<int> L, M, R;
	Loop (i,0,n) {
		(get2(a, i, 0) < v? L:
		 get2(a, i, 0) > v? R:
		                    M).push_back(i);
	}
	if (L.size()*2 > n || R.size()*2 > n)
		return -ans;
	if (M.size()*2 <= n)
		return ans;
	//cout << a << ' ' << b << '\n';
	//for (int x : M)
	//	cout << x << ' ';
	//cout << '\n';
	//for (int x : M) {
	//	int sz = 1;
	//	for (int y : M) {
	//		if (x == y || get2(x, a, b) + get2(y, a, b) == get(x, y))
	//			continue;
	//		sz++;
	//	}
	//	if (sz*2 > n)
	//		return -ans;
	//}
	dsu::init();
	//for (int x : M) for (int y : M) {
	//	x = dsu::rt(x);
	//	y = dsu::rt(y);
	//	if (x == y || get2(x, a, b) + get2(y, a, b) == get(x, y))
	//		continue;
	//	dsu::unite(x, y);
	//	//cout << x << ' ' << y << " -> " << dsu::sz[x] << '\n';
	//	if (dsu::sz[x]*2 > n)
	//		return -ans;
	//}
	for (int dard = 0; sub >= 3 && dard < 200000 && cnt < 5*n; ++dard) {
		vector<int> vec, sz;
		for (int v : M) {
			if (dsu::par[v] != -1)
				continue;
			vec.push_back(v);
			sz.push_back(dsu::sz[v] * dsu::sz[v]);
		}
		//int x = dsu::rt(M[rd()%M.size()]);
		int y = dsu::rt(M[rd()%M.size()]);
		int x = sel(sz);
		x = vec[x];
		//vector<int> vec;
		//for (int v : M) {
		//	int r = rt(v);
		//	if (r != x)
		//		vec.push_back(r);
		//}
		//int y = vec[rd()%vec.size()];
		if (x == y || get2(x, a, 0) + get2(y, a, 0) == get(x, y))
			continue;
		dsu::unite(x, y);
		//cout << x << ' ' << y << " -> " << dsu::sz[x] << '\n';
		if (dsu::sz[x]*2 > n)
			return -ans;
	}
	return ans;
}

Compilation message (stderr)

towns.cpp: In function 'int find_hub(int, int, int, int)':
towns.cpp:58:15: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
   58 |   if (get2(a, i, 0) == r)
      |               ^
towns.cpp:60:15: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
   60 |   if (get2(a, i, 0) == get(a, b) - r)
      |               ^
towns.cpp:62:7: warning: declaration of 'x' shadows a previous local [-Wshadow]
   62 |   int x = get2(a, i, 0);
      |       ^
towns.cpp:55:7: note: shadowed declaration is here
   55 |  bool x = 0, y = 0;
      |       ^
towns.cpp:62:19: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
   62 |   int x = get2(a, i, 0);
      |                   ^
towns.cpp:63:7: warning: declaration of 'y' shadows a previous local [-Wshadow]
   63 |   int y = get(a, b) - x;
      |       ^
towns.cpp:55:14: note: shadowed declaration is here
   55 |  bool x = 0, y = 0;
      |              ^
towns.cpp:64:27: warning: conversion from 'll' {aka 'long long int'} to 'std::vector<int>::value_type' {aka 'int'} may change value [-Wconversion]
   64 |   (x < y? Y: X).push_back(i);
      |                           ^
towns.cpp:70:17: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   70 |  if (X.size()*2 > n)
      |      ~~~~~~~~~~~^~~
towns.cpp:72:17: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   72 |  if (X.size()*2 == n)
      |      ~~~~~~~~~~~^~~~
towns.cpp: In function 'int sel(const std::vector<int>&)':
towns.cpp:81:15: warning: conversion from 'std::mersenne_twister_engine<long unsigned int, 64, 312, 156, 31, 13043109905998158313, 29, 6148914691236517205, 17, 8202884508482404352, 37, 18444473444759240704, 43, 6364136223846793005>::result_type' {aka 'long unsigned int'} to 'int' may change value [-Wconversion]
   81 |  int x = rd() % sum;
      |          ~~~~~^~~~~
towns.cpp:3:40: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    3 | #define Loop(x,l,r) for (ll x = (l); x < (r); ++x)
      |                                        ^
towns.cpp:82:2: note: in expansion of macro 'Loop'
   82 |  Loop (i,0,val.size()) {
      |  ^~~~
towns.cpp:84:11: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
   84 |    return i;
      |           ^
towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:94:20: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
   94 |   dis0[i] = get(0, i);
      |                    ^
towns.cpp:95:36: warning: conversion from 'long int' to 'int' may change value [-Wconversion]
   95 |  int a = max_element(dis0, dis0+n) - dis0;
      |          ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
towns.cpp:97:20: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
   97 |   disa[i] = get(a, i);
      |                    ^
towns.cpp:98:36: warning: conversion from 'long int' to 'int' may change value [-Wconversion]
   98 |  int b = max_element(disa, disa+n) - disa;
      |          ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
towns.cpp:103:19: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
  103 |   int x = get2(a, i, 0);
      |                   ^
towns.cpp:112:12: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
  112 |   (get2(a, i, 0) < v? L:
      |            ^
towns.cpp:113:12: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
  113 |    get2(a, i, 0) > v? R:
      |            ^
towns.cpp:114:36: warning: conversion from 'll' {aka 'long long int'} to 'std::vector<int>::value_type' {aka 'int'} may change value [-Wconversion]
  114 |                       M).push_back(i);
      |                                    ^
towns.cpp:116:17: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  116 |  if (L.size()*2 > n || R.size()*2 > n)
      |      ~~~~~~~~~~~^~~
towns.cpp:116:35: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  116 |  if (L.size()*2 > n || R.size()*2 > n)
      |                        ~~~~~~~~~~~^~~
towns.cpp:118:17: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  118 |  if (M.size()*2 <= n)
      |      ~~~~~~~~~~~^~~~
towns.cpp:147:12: warning: declaration of 'v' shadows a previous local [-Wshadow]
  147 |   for (int v : M) {
      |            ^
towns.cpp:107:6: note: shadowed declaration is here
  107 |  int v = find_hub(a, b, n, ans);
      |      ^

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