Submission #120832

#	Time	Username	Problem	Language	Result	Execution time	Memory
120832		Bruteforceman	도시들 (IOI15_towns)	C++11	13 / 100	21 ms	384 KiB

towns

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

map <pair <int, int>, int> mp;

int distance(int i, int j) {
	if(i == j) return 0;
	if(i > j) swap(i, j);
	if(mp.find(make_pair(i, j)) != mp.end()) return mp[make_pair(i, j)];
	return mp[make_pair(i, j)] = getDistance(i, j);
}

int hubDistance(int N, int sub) {
	mp.clear();
	int opt = 0;
	int dist = 0;
	for(int i = 1; i < N; i++) {
		int d = distance(0, i);
		if(d > dist) {
			dist = d;
			opt = i;
		}
	}
	int P = 0, Q = opt;
	dist = 0;
	for(int i = 0; i < N; i++) {
		if(i == opt) continue;
		int d = distance(opt, i);
		if(d > dist) {
			dist = d;
			P = i;
		}
	}


	map <int, int> dist_chain;

	int R = distance(P, Q);
	for(int i = 0; i < N; i++) {
		int lca_dist = (distance(i, P) + distance(i, Q) - distance(P, Q)) / 2;
		int p_dist = distance(i, P) - lca_dist;
		R = min(R, max(p_dist, distance(P, Q) - p_dist));
		dist_chain[i] = lca_dist;
	}
	int root = 0;
	for(int i = 0; i < N; i++) {
		int lca_dist = (distance(i, P) + distance(i, Q) - distance(P, Q)) / 2;
		int p_dist = distance(i, P) - lca_dist;
		int val = max(p_dist, distance(P, Q) - p_dist);
		if(val == R && distance(i, P) + distance(i, Q) == distance(P, Q)) {
			root = i;
			break;
		}
	}

	vector <int> unmatched;

	for(int i = 0; i < N; i++) {
		if(i == root) continue;
		if(unmatched.empty()) {
			unmatched.push_back(i);
			continue;
		}
		int d1 = distance(root, i);
		int d2 = distance(root, unmatched.back());
		int d3 = distance(i, unmatched.back());
		if(d1 + d2 == d3) {
			unmatched.pop_back();
		} else {
			unmatched.push_back(i);
		}
	}
	if(unmatched.empty()) return R;
	int piv = unmatched.back();

	int cnt = 0;
	for(int i = 0; i < N; i++) {
		if(i == root) continue;
		int d1 = distance(root, i);
		int d2 = distance(root, piv);
		int d3 = distance(i, piv);
		if(d1 + d2 != d3) {
			++cnt;
		}
	}
	if(cnt > (N / 2)) R *= -1;
	return R;
}

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:14:28: warning: unused parameter 'sub' [-Wunused-parameter]
 int hubDistance(int N, int sub) {
                            ^~~

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