Submission #557702

#	Time	Username	Problem	Language	Result	Execution time	Memory
557702		sidon	Towns (IOI15_towns)	C++17	100 / 100	25 ms	616 KiB

towns

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

int hubDistance(int N, int _) {
	int d[200][200] {}, x {};
	for(int i = 1; i < N; ++i)
		if((d[0][i] = getDistance(0, i)) > d[0][x])
			x = i;
	int y = x;
	for(int i = 0; i < N; ++i)
		if((d[x][i] = getDistance(x, i)) > d[x][y])
			y = i;

	int R = 1e6, c[N], h = -1;
	array<int, 2> cR {R};

	for(int i = 0; i < N; ++i) {
		c[i] = (d[x][i] - d[0][i] + d[0][x]) / 2;
		R = min(R, max(c[i], d[x][y] - c[i]));
		if(i && i != x) {
			cR[0] = min(cR[0], c[i]);
			cR[1] = max(cR[1], c[i]);
		}
	}

	for(int i = 0; i < N; ++i) if(R == max(c[i], d[x][y] - c[i])) {
		int cnt[2] {};
		for(int j = 0; j < N; ++j) if(c[i] != c[j])
			++cnt[c[j] > c[i]];
		while(!(cnt[0] + cnt[1]));
		if(max(cnt[0], cnt[1]) <= N/2) h = i;
	}
	if(h < 0) return -R;
	c[0] = cR[1], c[x] = cR[0];
	d[x][x] = 2 * c[x];

	auto same = [&](int i, int j) {
		return i == j || getDistance(i, j) < d[x][i] + d[x][j] - 2 * c[h];
	};

	int cnt {}, val {}, w[N] {};
	map<int, bool> bad;

	for(int i = 0; i < N; ++i) if(c[i] == c[h]) {
		if(!cnt) val = i, bad.clear();

		if(same(i, val)) ++cnt, ++w[val];
		else --cnt, w[i] = 1, bad[i] = 1;
	}

	cnt = 0;
	for(int i = 0; i < N; ++i)
		if(!bad[i] && w[i] && same(i, val)) cnt += w[i];

	return cnt > N/2 ? -R : R;
}

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:5:28: warning: unused parameter '_' [-Wunused-parameter]
    5 | int hubDistance(int N, int _) {
      |                        ~~~~^

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