Submission #1021139

#	Time	Username	Problem	Language	Result	Execution time	Memory
1021139		AmirAli_H1	Towns (IOI15_towns)	C++17	100 / 100	23 ms	1116 KiB

towns

// In the name of Allah

#include <bits/stdc++.h>
#include "towns.h"
using namespace std;

typedef		long long int			ll;
typedef		long double				ld;
typedef		pair<int, int>			pii;
typedef		pair<ll, ll>			pll;
typedef		complex<ld>				cld;

#define		all(x)					(x).begin(),(x).end()
#define		len(x)					((ll) (x).size())
#define		F						first
#define		S						second
#define		pb						push_back
#define		sep						' '
#define		endl					'\n'
#define		Mp						make_pair
#define		kill(x)					cout << x << '\n', exit(0)
#define		set_dec(x)				cout << fixed << setprecision(x);
#define		file_io(x,y)			freopen(x, "r", stdin); freopen(y, "w", stdout);
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int n;
int v1, v2, u1, u2;
const int maxn = 110 + 4;
ll dis[maxn][maxn], R;
int p[maxn], sz[maxn];

int get(int a) {
	return (p[a] == a) ? a : p[a] = get(p[a]);
}

void merge(int a, int b) {
	a = get(a); b = get(b);
	if (a == b) return ;
	if (sz[a] > sz[b]) swap(a, b);
	p[a] = b; sz[b] += sz[a]; sz[a] = 0;
}

ll get_dis(int u, int v) {
	if (dis[u][v] == -1) {
		dis[u][v] = dis[v][u] = getDistance(u, v);
	}
	return dis[u][v];
}

bool ok(ll R) {
	bool flag = 0;
	ll dx = get_dis(v1, v2);
	for (int i = 0; i < n; i++) {
		ll d1 = get_dis(v1, i), d2 = get_dis(v2, i);
		ll x = (d1 + d2 - dx) / 2;
		if (d2 - x == R) {
			flag = 1;
			break;
		}
	}
	if (!flag) return 0;
	
	int t1 = 0, t2 = 0;
	for (int i = 0; i < n; i++) {
		ll d1 = get_dis(v1, i), d2 = get_dis(v2, i);
		ll x = (d1 + d2 - dx) / 2;
		if (d2 - x < R) t1++;
		else if (d2 - x > R) t2++;
	}
	return (max(t1, t2) * 2 <= n);
}

void check(int i, int j) {
	ll dx = get_dis(v1, v2);
	ll d1 = get_dis(v1, i), d2 = get_dis(v2, i);
	ll x1 = (d1 + d2 - dx) / 2;
	d1 = get_dis(v1, j), d2 = get_dis(v2, j);
	ll x2 = (d1 + d2 - dx) / 2;
	ll valx = (x1 + x2 - get_dis(i, j)) / 2;
	if (valx > 0) merge(i, j);
	return ;
}

int hubDistance(int N, int sub) {
	n = N;
	
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			if (i == j) dis[i][j] = 0;
			else dis[i][j] = -1;
		}
	}
	
	v1 = 0, u1 = v1;
	for (int i = 0; i < n; i++) {
		if (get_dis(v1, i) > get_dis(v1, u1)) u1 = i;
	}
	
	v2 = u1, u2 = v2;
	for (int i = 0; i < n; i++) {
		if (get_dis(v2, i) > get_dis(v2, u2)) u2 = i;
	}
	
	ll dx = get_dis(v1, v2);
	ll D = get_dis(u1, u2); R = D;
	for (int i = 0; i < n; i++) {
		ll d1 = get_dis(v1, i), d2 = get_dis(v2, i);
		ll x = (d1 + d2 - dx) / 2;
		R = min(R, max(d2 - x, D - (d2 - x)));
	}
	
	if (!ok(R) && !ok(D - R)) return -R;
	
	iota(p, p + n, 0); fill(sz, sz + n, 1);
	int v = 0, cnt = 1;
	for (int i = 1; i < n; i++) {
		if (cnt == 0) {
			v = i; cnt = 1;
		}
		else {
			check(i, v);
			if (get(i) == get(v)) cnt++;
			else cnt--;
		}
	}
	
	for (int i = 0; i < n; i++) {
		if (get(i) != i || get(i) == get(v)) continue;
		check(i, v);
	}
	
	if (sz[get(v)] * 2 <= n) return R;
	else return -R;
}

Compilation message (stderr)

towns.cpp: In function 'bool ok(ll)':
towns.cpp:50:12: warning: declaration of 'R' shadows a global declaration [-Wshadow]
   50 | bool ok(ll R) {
      |         ~~~^
towns.cpp:29:21: note: shadowed declaration is here
   29 | ll dis[maxn][maxn], R;
      |                     ^
towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:112:35: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
  112 |  if (!ok(R) && !ok(D - R)) return -R;
      |                                   ^~
towns.cpp:132:34: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
  132 |  if (sz[get(v)] * 2 <= n) return R;
      |                                  ^
towns.cpp:133:14: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
  133 |  else return -R;
      |              ^~
towns.cpp:84:28: warning: unused parameter 'sub' [-Wunused-parameter]
   84 | 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